Substituted complexing agents, complexes, and complex salts, processes for their production, and pharmaceuticals containing same

ABSTRACT

1. Compounds of general Formula I ##STR1## wherein n and m in each case mean the numbers 0, 1, 2, 3 and 4, 
     X stands for a hydrogen atom and/or a metal ion equivalent of an element of atomic numbers 21-29, 31, 32, 37-39, 42-44, 49 or 57-83, 
     R 1  and R 2 , being different, mean in each case a hydrogen atom or a straight-chain, branched, saturated or unsaturated C 0  -C 20  -alkylene group, this alkylene group exhibiting at the end either a second molecule of general Formula I A  or I B  ##STR2##  a functional group, or, linked by way of this functional group, a bio- or macromolecule, are valuable diagnostic and therapeutic media,

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser No.08/269,504, filed Jul. 1, 1994 now U.S. Pat. No. 5,482,700, herebyincorporated in its entirety, which is a continuation of Ser. No.08/066,646, filed May 25, 1993 (abandoned), which is a continuation ofSer. No. 07/715,713, filed Jun. 18, 1991 (abandoned), which is acontinuation of Ser. No. 07/430,442, filed Oct. 2, 1989 (abandoned),which is based on international application PCT/DE88/00199, filed Mar.28, 1988.

The invention relates to the subject matter characterized in the claims,i.e., novel complexing agents, complexes, and complex salts, mediacontaining these compounds, their use in diagnostics and therapy, aswell as processes for the production of these compounds and media.

The use of complexing agents or complexes and, respectively, their saltsin medicine has been known for a long time. The following examples canbe cited:

Complexing agents as stabilizers for pharmaceutical preparations,complexes and their salts as auxiliary media for administration ofpoorly soluble ions (e.g., iron), complexing agents and complexes(preferably calcium or zinc compounds), optionally in the form of saltswith inorganic and/or organic bases, as antidotes for detoxification incase of inadvertent ingestion of heavy metals, or their radioactiveisotopes and complexing agents as auxiliary media in nuclear medicineusing radioactive isotopes, such as ^(99m) Tc for scintigraphy, all havebeen known. Recently, patent publication DOS 3,401,052 has suggestedparamagnetic complex salts as diagnostic media, predominantly as NMRdiagnostic media.

All of the heretofore known complexes and their salts cause problems intheir clinical usage with respect to compatibility and/or selectivity ofbinding and/or stability. These problems become the more pronounced, thehigher the dosages that must be utilized for the products derived fromthe complexing agents. Use of heavy elements, inherently beneficial, ascomponents of X-ray contrast media to be administered parenterally hasfailed thus far due to inadequate compatibility of such compounds. Inthe paramagnetic materials heretofore proposed or tested for NMRtomography, the interval between the effective dose and the dose toxicin animal experiments is relatively narrow and/or the materials show loworgan specificity and/or stability and/or contrast-enhancing effectand/or their compatibility is insufficient.

Only very limited success has been achieved thus far in attempting tosolve at least part of these problems by the use of complexing agentsbound, on the one hand, by ionic linkage to the respectively suitablemetal (see below) as well as, on the other hand, by linkage to afunctional group or to a macromolecule that is nontoxic and maximallyorgan-specific and serves as the carrier molecule.

When utilizing the functional groups of the complexing agent for linkingthe molecule to a bio-molecule, then complex stability is weakened, i.e.a physiologically intolerable proportion of the metal ions of themacromolecule-metal ion complex is liberated C. H. Paik et al., J.Radioanal. Chem. 57: 553 (1980); D. J. Hnatowich et al., J. Nucl. Med.26: 503 (1985)!.

On the other hand, when using as the educts bifunctional complexingagents, i.e. complexing compounds carrying functional groups forcoordinative linkage of the desired metal ion as well as a.(different)functional group for binding the macromolecule, then a great variety ofgrave disadvantages occur according to the present state of the art (C.F. Meares et al., Radioimmunoimaging and Radioimmunotherapy 1983: 185;Canadian Patent No. 1,178,951): There are, for example, low stability ofthe complexes, multistage, difficult synthesis of the complexes, smallvariation possibilities of the functional group required for binding tothe macromolecule, danger of contamination of the complexing agentsduring their synthesis with foreign metals, only limited reactionpossibilities of the complexing agents on account of a lipophily that istoo low, required intermediate blockage of the functional groups of thecomplexing agents (e.g. as iron complex or blockage of a phenolichydroxy group as the methyl ether) accompanied by a reduction in yieldand additional purification steps, necessity of having to work withhighly purified solvents and apparatuses.

Therefore, there is a need, for variegated purposes, for stable, readilysoluble and adequately selective, but also more compatible, easilyaccessible complex compounds exhibiting a maximum variety of functionalgroups suitable for linkage to macromolecules. Therefore, the inventionis based on the object of making these compounds and media available aswell as of providing a maximally simple process for their production.This object has been attained by the invention.

It has been found that compounds consisting of the anion of amonofunctionalized aminopolycarboxylic acid and one or several centralions of an element of atomic numbers 21-29, 31, 32, 37-39, 42-44, or57-83, as well as optionally one or several cations of an inorganicand/or organic base or amino acid are surprisingly excellently suitablefor the production of NMR, X-ray and radiodiagnostic media, as well asradio-therapeutic media.

The compounds according to this invention are described by generalFormula I ##STR3## wherein n and m in each case mean the numbers 0, 1,2, 3 and 4,

X stands for a hydrogen atom and/or a metal ion equivalent of an elementof atomic numbers 21-29, 31, 32, 37-39, 42-44, 49 or 57-83,

R¹ and R² being different mean in each case a hydrogen atom or astraight-chain, branched, saturated or unsaturated C₀ -C₂₀ -alkylenegroup which optionally contains imino, phenylenoxy, phenylenimino,amido, hydrazido, ester group(s), oxygen, sulfur and/or nitrogen atom(s)and is substituted, if desired, by hydroxy, mercapto, imino, epoxy, oxo,thioxo and/or amino group(s), this alkylene group exhibiting at the endeither a second molecule of general Formula I_(A) or I_(B) ##STR4## afunctional group, or, linked by way of this functional group, a bio- ormacromolecule,

with the proviso that n and m jointly do not result in more than 4 andthat, if X means a metal ion equivalent, at least two of thesubstituents X have this meaning.

Compounds of general Formula I wherein X means hydrogen are denoted ascomplexing agents and, with at least two of the substituents X meaning ametal ion equivalent, are denoted as metal complexes.

The element of the above-mentioned atomic number constituting thecentral ion of the physiologically compatible complex salt can, ofcourse, also be radioactive for the intended utilization of thediagnostic medium according to this invention.

If the medium of this invention is meant for NMR diagnostics, then thecentral ion of the complex salt must be paramagnetic. This means, inparticular, the divalent and trivalent ions of the elements of atomicnumbers 21-29, 42, 44, and 58-70. Suitable ions are, for example, thechromium(III), manganese(II), iron(II), cobalt(II), nickel(II),copper(II), praseodymium(III), neodymium(III), samarium(III) andytterbium(III) ions. On account of their very strong magnetic moment,especially preferred are gadolinium(III), terbium(III), dysprosium(III),holmium(III), erbium(III) and iron(III) ions.

For using the media of this invention in nuclear-medicine diagnostics,the central ion must be radioactive. Suitable are, for example,radioisotopes of the elements copper, cobalt, gallium, germanium,yttrium, strontium, technetium, indium, gadolinium, samarium andiridium.

For use of the media according to this invention in nuclear medicine,the central ion must be radio-active. Suitable are, for instance,radioisotopes of the elements copper, cobalt, gallium, germanium,yttrium, strontium, technetium, indium, ytterbium, gadolinium, samariumand iridium.

If the medium of this invention is intended for use in X-raydiagnostics, then the central ion must be derived from an element of ahigher atomic number in order to achieve adequate absorption of theX-rays. It has been found that this requirement is met by diagnosticmedia containing a physiologically compatible complex salt with centralions of elements of atomic numbers of between 21 and 29, 42, 44, 57-83;these are, for example, the lanthanum(III) ion and the above-cited ionsof the lanthanide series.

The alkylene group contained in R¹ and R², respectively, can bestraight-chain, branched, cyclic, aliphatic, aromatic or arylaliphaticand can contain up to 20 carbon atoms. Preferred are straight-chainmono- to hexamethylene groups as well as C₁ -C₄ -alkylenephenyl groups.In case the alkylene group contains a phenoxy group, the latter islinked preferably in the p-position via a methylene group to the--CH-group of the basic skeleton of the compound according to generalFormula I.

Preferred functional groups present at the end of the R¹ and,respectively, R² alkylene group are, for example, the benzyl ester,ethyl ester, tert-butyl ester, amino, C₁ -C₆ -alkylamino, aminocarbonyl,hydrazino, hydrazinocarbonyl, maleimido, methacrylamido,methacryloylhydrazinocarbonyl, maleimidamidocarbonyl, halo, mercapto,hydrazinotrimethylenehydrazinocarbonyl, aminodimethylenamidocarbonyl,bromocarbonyl, phenylenediazonium, isothiocyanate, semicarbazide,thiosemicarbazide groups.

For explanatory purposes, several selected R¹ and, respectively, R²substituents are listed below: ##STR5## wherein R and R' being identicalor different, mean respectively a hydrogen atom, a saturated orunsaturated C₁ -C₂₀ -alkyl residue optionally substituted by a phenylgroup, or a phenyl group.

In case not all of the acidic hydrogen atoms are substituted by thecentral ion, it is possible to replace one, several or all of theremaining hydrogen atom(s) by cations of inorganic and/or organic basesor amino acids. Suitable inorganic cations are, for example, the lithiumion, the potassium ion, the calcium ion and, in particular, the sodiumion. Suitable cations of organic bases are, inter alia, those ofprimary, secondary or tertiary amines, e.g. ethanolamine,diethanolamine, morpholine, glucamine, N,N-dimethylglucamine andespecially N-methylglucamine. Suitable cations of amino acids are, forexample, those of lysine, of arginine and of ornithine.

The complexing agents according to this invention are produced bysaponifying compounds of general Formula II ##STR6## wherein n and mhave the meanings given above, R^(1') and R^(2') are different and ineach case mean a hydrogen atom or a straight-chain, branched, saturatedor unsaturated C₀ -C₂₀ -alkylene group optionally containing imino,phenylenoxy, phenylenimino, amido, hydrazido, ester group(s), oxygen,sulfur and/or nitrogen atom(s) and, if desired, substituted by hydroxy,mercapto, imino, epoxy, oxo, thioxo and/or amino group(s), this alkylenegroup exhibiting at the end a second molecule of general Formula I'_(A)or I'_(B) ##STR7## or a functional group, and R³ means a C₁ -C₆ -alkylresidue.

Saponification is conducted according to the methods known to personsskilled in the art, for example, in case of tert-butyl esters, with theaid of trifluoroacetic acid.

The educts are prepared by alkylation of monosubstituted polyamines ofgeneral Formula III ##STR8## wherein n and m each stands for the numbers0, 1, 2, 3 and 4, and R^(1") and R^(2") respectively mean a hydrogenatom or a substituent which can be converted into R^(1') and R^(2'),respectively,

with the proviso that n and m jointly are no more than 4, that thesubstituents R^(1") and R^(2") are different and one stands for ahydrogen atom and the other for a substituent convertible into R^(1')and R^(2') respectively,

with an ester of general Formula IV

    HalCH.sub.2 COOR.sup.3                                     (IV)

wherein Hal means chorine, bromine or iodine and R³ has the meaningsgiven for general Formula II.

The reaction takes place in polar aprotic solvents, such as, forexample, dimethylformamide, dimethyl sulfoxide or hexamethylphosphorictriamide in the presence of an acid neutralizer, e.g. tertiary amine(e.g. triethylamine, trimethylamine, N,N-dimethylaminopyridine,1,5-diazabicyclo 4.3.0!nonene-5 DBN!, 1,5-diazabicyclo5.4.0!undecene-5), alkali, alkaline earth carbonate or bicarbonate (forexample, sodium, magnesium, calcium, barium, potassium carbonate andbicarbonate) at temperatures of between -10° C. and 120° C., preferablybetween 0° C. and 50° C.

Methods known from the literature are employed for the synthesis ofdimers, i.e. compounds of general Formula I wherein the C₀ -C₂₀-alkylene group contained in R¹ and R² is bound to a second molecule ofgeneral Formula I_(A) or I_(B), for example by way of anaddition/elimination reaction of an amine with a carbonyl compound (e.g.acid chloride, mixed anhydride, activated ester, aldehyde); of twoamine-substituted rings with a dicarbonyl compound (for example oxalylchloride, glutaric dialdehyde); of two rings each exhibiting anucleophilic group, with an alkylene compound carrying two leavinggroups or, in case of terminal acetyls, by oxidative coupling (Cadiot,Chodkiewicz in Viehe "Acetylenes", 597-647, Marcel Dekker, New York,1969).

The chain linking the two halves of the molecule can subsequently bemodified by follow-up reactions (e.g. hydrogenation).

Suitable substituents R^(1") and R^(2"), respectively, are, inter alia,hydroxy and nitrobenzyl, hydroxy and carboxyalkyl, as well as thioalkylresidues of up to 10 carbon atoms. They are converted by means ofmethods of the literature known to those skilled in the art Chem.-Pharm.Bull. 33: 674 (1985), Compendium of Org. Synthesis, vol. 1-5, Wiley andSons, Inc.! into the desired substituents (e.g. with the amino,hydrazino, hydrazinocarbonyl, methacryloylhydrazinocarbonyl,maleimidamidocarbonyl, halo, halocarbonyl, mercapto group as thefunctional group) wherein, in case of the nitrobenzyl residue, acatalytic hydrogenation must first be performed to the aminobenzylderivative (for example in accordance with P. N. Rylander, CatalyticHydrogenation Over Platinum Metals, Academic Press 1967).

Examples for the conversion of hydroxy or amino groups linked toaromatic or aliphatic residues are the reactions, performed inanhydrous, aprotic solvents such as tetrahydrofuran, dimethoxyethane ordimethyl sulfoxide in the presence of an acid neutralizer, such as, forexample, sodium hydroxide, sodium hydride or alkali or alkaline earthcarbonates, such as, for example, sodium, magnesium, potassium, calciumcarbonate, at temperatures of between 0° C. and the boiling point of therespective solvent, but preferably between 20° C. and 60° C., with asubstrate of general Formula V

    Z--L--Fu                                                   (V)

wherein Z is a nucleofugal entity, such as, for example, Cl, Br, I, CH₃C₆ H₄ SO₃ or CF₃ SO₃, L is an aliphatic, aromatic, arylaliphatic,branched, straight-chain or cyclic hydrocarbon residue of up to 20carbon atoms, and Fu means the desired end-positioned functional group,optionally in blocked form (DOS 3,417,413).

Examples that can be cited for compounds of general Formula V are

Br(CH₂)₂ NH₂, Br(CH₂)₃ OH, BrCH₂ COOCH₃, BrCH₂ CO₂ ^(t) Bu, Br(CH₂)₄ CO₂C₂ H₅, BrCH₂ COBr, BrCH₂ CONH₂ ClCH₂ COOC₂ H₅ BrCH₂ CONHNH₂, ##STR9##BrCH₂ C.tbd.CH, BrCH₂ CH═CH₂.

Conversions of carboxy groups can be performed, for example, accordingto the carbodiimide method (Fieser, Reagents for Organic Syntheses, 10:142) via a mixed anhydride Org. Prep. Proc. Int. 7: 215 (1975)! or viaan activated ester (Adv. Org. Chem. Part B, 472).

The amines of general Formula III required as the starting compounds areprepared analogously to methods known from the literature (for example,Canad. Patent No. 1,178,951, Eur. I. Med. Chem.-Chim. Ther. 1985, 20:509, and 1986, 21: 333) by starting with amino acids which are convertedinto amides that are optionally substituted with ethylenamine e.g. withN-(2-aminoethyl)carbamic acid benzyl ester! and then are reduced to thedesired amines (preferably with diborane or lithium aluminum hydride).

If compounds are to be synthetized according to general Formula I whereR¹ means a hydrogen atom, then it is necessary to substitute such anamide prior to reduction on the α-amino group by reacting with, forexample, ethyl oxamate in a polar solvent, e.g. tetrahdyrofuran,dimethyl sulfoxide or dimethoxyethane, at a temperature of between 50°C. and 250° C., preferably 70° C. to 150° C. (optionally in apressurized vessel) so that a 3-aza-2-oxoglutaric acid diamidederivative is obtained as the intermediate.

The resultant complex-forming ligands (as well as the complexes) canalso be linked to bio- or macromolecules of which it is known that theyare especially enriched in the organ or organ part to be investigated.Such molecules are, for example, enzymes, hormones, sugars, dextrans,lectins, porphyrins, bleomycins, insulin, prostaglandins, steroidhormones, amino sugars, amino acids, peptides, such as polylysine,proteins (e.g. immunoglobulins and monoclonal antibodies) or lipids(also in the form of liposomes). Conjugates with albumins, such as humanserum albumin, antibodies, such as, for example, monoclonal antibodiesspecific for tumor-associated antigens, antimyosin or cholic acid can beemphasized, in particular. Instead of biomolecules, it is also possibleto link suitable synthetic polymers, such as polyethylenimines,polyamides, polyureas, polyethers and polythioureas. The resultantpharmaceutical agents are suited, for example, for use in tumor andinfarction diagnostics, as well as in tumor therapy. Suitable monoclonalantibodies (e.g. Nature 256: 495, 1975), having the advantages over thepolyclonal antibodies of being specific for an antigen determinant,exhibiting defined binding affinity, being homogeneous (thussubstantially facilitating their production in pure form), and beingproducible in cell cultures in large amounts, are especially those forthe conjugation which are directed against predominantlycell-membrane-located antigens. Suitable as those are, for example, fortumor imaging monoclonal antibodies and/or their fragments Fab andF(ab')₂ which are specific, for example, for human tumors of thegastrointestinal tract, of the breast, the liver, the bladder, thereproductive glands, and of melanomas (Cancer Treatment Repts. 68: 317,1984, Bio. Sci. 34: 150, 1984) or against Carcinoembryonales Antigen(CEA), Humanes Choriogonadotropin (β-HCG), or other tumor-locatedantigens, such as glycoproteins (New Engl. J. Med. 298: 1384, 1973, U.S.Pat. No. 4,331,647). Likewise suitable are, inter alia, anti-myosin,anti-insulin and anti-fibrin antibodies (U.S. Pat. No. 4,036,945).

Suited for liver tests and gallbladder-diagnostics or tumor diagnosticsare the monomeric complexes as well as conjugates or clathrates withliposomes (used, for example, as unilamellar or multi-lamellarphosphatidyl choline cholesterol vesicles).

The linkages known from the state of the art of, for example,radioisotopes to immunoglobulins and their fragments suffer from thedisadvantage of lack of stability of the labeled antibody conjugatesand/or lack of specificity (for example on account of the use of adiethylenetriaminepentaacetic acid=DTPA anhydride)(for example,Diagnostic Imaging 84: 56; Science 220: 613, 1983; Cancer Drug Delivery1: 125, 1984).

In contrast thereto, the formation of the conjugate in accordance withthe present invention takes place by way of the functional group locatedat the end of the C₀ -C₂₀ -alkylene group of substituent R¹ or R², asdefined hereinabove. In the conjugate formation of the acids with bio-or macromolecules, several acid residues can be bound to the latter. Inthis case, each acid residue can carry a central ion.

Coupling to the desired macromolecules likewise takes place according tomethods known per se, as described, for example, in Rev. Roum. Morphol.Embryol. Physio., Physiologie 1981, 18: 241 and J. Pharm. Sci. 68: 79(1979), for example by reacting the nucleophilic group of amacromolecule, such as the amino, phenol, sulfhydryl, aldehyde orimidazole group, with an activated derivative of the complexing agent.Examples of suitable activated derivatives are mono-anhydrides, acidchlorides, acid hydrazides, mixed anhydrides (see, for example, G. E.Krejcarek and K. L. Tucker, Biochem., Biophys. Res. Commun. 1977: 581),activated esters, nitrenes or isothiocyanates. Conversely, it is alsopossible to react an activated macromolecule with the complexing acid.For the conjugation with proteins, likewise suitable are substituentshaving, for example, the structure C₆ H₄ N₂, C₆ H₄ NHCOCH₂, C₆ H₄ NHCSor C₆ H₄ OCH₂ CO.

In case of the antibody conjugates, the linkage of the antibody to thecomplexing agent (or to the metal complex; production of the metalcomplex conjugate can take place in the sequence of complexing agent,complexing agent-conjugate, final product, as well as in the sequencecomplexing agent, metal complex, final product) must not lead to loss orreduction of binding affinity and binding specificity of the antibody tothe antigen. This can be accomplished either by linkage to thecarbohydrate portion in the Fc part of the glycoprotein or,respectively, in the Fab or F(ab')₂ fragments; or by linkage to sulfuratoms of the antibody or of the antibody fragments.

In the former case, an oxidative splitting of sugar units must first becarried out to generate formyl groups capable of coupling. Thisoxidation can take place by chemical methods with oxidizing agents suchas, for example, periodic acid, sodium metaperiodate or potassiummetaperiodate in accordnace with processes known from the literature(e.g. J. Histochem. and Cytochem. 22: 1084, 1974) in an aqueous solutionin concentrations of 1-100, preferably 1-20 mg/ml, and with aconcentration of the oxidizing agent of between 0.001 and 10 millimoles,preferably 1-10 mmol, in a pH range of about 4-8 at a temperature ofbetween 0° and 37° C. and with a reaction period of between 15 minutesand 24 hours. The oxidation can also be performed by an enzymaticmethod, for example with the aid of galactose oxidase in an enzymeconcentration of 10-100 units/ml, a substrate concentration of 1-20mg/ml, at a pH of 5-8, a reaction time of 1-8 hours, and at atemperature of between 20° and 40° C. (for example J. Biol. Chem. 234:445, 1959).

Complexing agents (or metal complexes, see above) with suitablefunctional groups, e.g. hydrazine, hydrazide, primary amine,hydroxylamine, phenyl-hydrazine, semicarbazide and thiosemicarbazide arelinked to the aldehydes generated by oxidation, by reaction at between0° and 37° C., with a reaction period of 1-65 hours, a pH of betweenabout 5.5 and 8, an antibody concentration of 0.5-20 mg/ml, and a molarratio of the complexing agent to the antibody aldehyde of 1:1 to 1000:1.The subsequent stabilization of the conjugate takes place by reductionof the double bond, for example with sodium borohydride or sodiumcyanoborohydride; the reducing agent is utilized in this process in a10- to 100-fold excess (for example, J. Biol. Chem. 254: 4359, 1979).

The second possibility of forming antibody conjugates starts with agentle reduction of the disulfide bridges of the immunoglobulinmolecule; in this step, the more sensitive disulfide bridges of theH-chains of the antibody molecule are cleaved while the S-S-linkages ofthe antigen-binding region remain intact so that there is practically nodiminution of the binding affinity and specificity of the antibody(Biochem. 18: 2226, 1979, Handbook of Experimental Immunology, vol. 1,Second Edition, Blackwell Scientific Publications, Lindon 1973, chapter10). These free sulfhydryl groups of the intra-H-chain regions are thenreacted with suitable functional groups of complexing agents or metalcomplexes at 0°-37° C., a pH of about 4-7, and a reaction time of 3-72hours with the formation of a covalent bond not affecting the antigenbinding region of the antibody. Examples of suitable reactive groupsare: haloalkyl, haloacetyl, p-mercuribenzoate groups, as well as groupsto be subjected to a Michael addition reaction, such as, for example,maleinimides, methacrylo groups (for example J. Amer. Chem. Soc. 101:3097, 1979).

It is also possible to utilize linkages of a non-covalent type forcoupling purposes; in this connection, ionic as well as van der Waalsand hydrogen bridge linkages can contribute toward the linking step invarying proportions and intensity (lock-and-key principle)(for example,avidin-biotin, antibody-antigen). Also clathrate compounds (host-guest)of relatively small complexes in relatively large cavities in themacromolecule are possible.

The coupling principle resides in initially producing a bifunctionalmacromolecule either by fusing an antibody hybridoma directed against atumor antigen with a second antibody hybridoma directed against acomplex according to this invention, or by linking the two antibodieswith each other chemically via a linking agent for example in the mannerdisclosed in J. Amer. Chem. Soc. 101: 3097 (1979)! or binding theantibody directed against the tumor antigen to avidin (or biotin), ifneeded, by way of a linking agent D. J. Hnatowich et al., J. Nucl. Med.28: 1294 (1987)!. Instead of the antibodies, it is also possible to usetheir corresponding F(ab) or F(ab')₂ fragments. For pharmaceuticalusage, the bifunctional macromolecule is injected first of all, thismolecule accumulating at the target site, and then, at a time interval,the complex compound optionally bound to biotin (or avidin)! is injectedwhich is coupled in vivo at the target site and can there deploy itsdiagnostic or therapeutic effect. Moreover, other coupling methods canlikewise employed, such as, for example, "reversible radiolabeling"described in Protein Tailoring Food Med. Uses Am. Chem. Soc. Symp.!(1985), 349.

A method especially well suited for the production of conjugates ofantibodies as well as antibody fragments is the coupling to a solidphase. In this process, the antibody or the corresponding F(ab)₂fragment is bound to a stationary phase (e.g. an ion exchanger) locatedin a column equipped with inlet and outlet and beingtemperature-controllable. For the oxidation in the Fc portion of theantibody, the column must be protected from the effect of light byproviding coverage; for the reduction of disulfide bridges (for examplein the generation of Fab fragments) the process must be performableunder argon as a protective gas. The actual coupling step then takesplace as follows:

After flushing of the column with a suitable buffer, a solution is usedas the eluent which produces reactive groups on the bound protein (forexample, periodate solution for the production of aldehyde groups in theFc portion of monoclonal antibodies or mercaptoethylamine solution forthe production of sulfhydryl groups in fragments). After the reactionsolution has completely displaced the previous eluent, throughflow isstopped for a time adequate for complete reaction, then adequateflushing is carried out with a buffer, whereafter a solution with thecoupling partner (e.g. the hydrazide or dithiopyridyl derivative of acomplexing agent or of a complex) is applied, and throughflow is oncemore stopped for an adequate time length. Instead of stoppingthroughflow for a relatively long period of time, it is also possible touse a so-called recycle circuit; in this process, the eluate leaving thecolumn is directly pumped back into the column by means of a loopcircuit. In this method, on account of improved intermixing,substantially shorter reaction times and higher yields are obtained.Thereafter, flushing is again performed with buffer solution. If a freecomplexing agent is the coupling partner, then, in a further cycle,complexing is conducted with a solution of the desired metal salt (forexample a citrate solution) as well as a subsequent flushing step.Finally, the conjugate is eluted with a pH gradient or salt gradient.Subsequently, a lyophilizing step is carried out, optionally afterdesalting. After equilibration with buffer solution, the column is readyfor the next coupling step.

This method, for the production of very small as well as very largequantities of conjugate, is far superior to the conventional methodswith respect to speed and also yield, and permits also the continuouspreparation of conjugates; this is the prerequisite for an economicalproduction of relatively large amounts.

The thus-formed compounds are subsequently purified preferably bychromatography via ion exchangers on a fast protein liquidchromatography facility.

The thus-obtained compounds of general Formula I wherein X means ahydrogen atom represent complex-forming agents. They can be isolated andpurified, or they can be converted without isolation into metalcomplexes of general Formula I with at least two of the substituents Xmeaning a metal ion equivalent.

The metal complexes of this invention are produced as disclosed in thepatent publication DOS 3,401,052, by dissolving or suspending the metaloxide or a metal salt (e.g. the nitrate, acetate, carbonate, chloride orsulfate) of the element of atomic numbers 21-29, 31, 32, 38, 39, 42-44,49, 57-83, in water and/or in a lower alcohol (such as methanol, ethanolor isopropanol) and reacting with a solution or suspension of theequivalent amount of the complexing acid of general Formula I wherein Xmeans a hydrogen atom, and subsequently, if desired, substituting anyacidic hydrogen atoms of acid groups that may be present by cations ofinorganic and/or organic bases or amino acids.

Neutralization takes place in this process with the aid of inorganicbases (for example hydroxides, carbonates or bicarbonates) of, forexample, sodium, potassium or lithium and/or of organic bases, such as,inter alia, primary, secondary and tertiary amines, e.g. ethanolamine,morpholine, glucamine, N-methyl- and N,N-dimethylglucamine, as well asalkaline amino acids, e.g. lysine, arginine and ornithine.

For producing the neutral complex compounds, such an amount of thedesired bases can, for example, be added to the acidic complex salts inan aqueous solution or suspension that the neutral point is attained.The thus-produced solution can then be evaporated to dryness undervacuum. It is frequently advantageous to precipitate the thus-formedneutral salts by adding water-miscible solvents, such as, for example,lower alcohols (methanol, ethanol, isopropanol and others), lowerketones (acetone and others), polar ethers (tetrahydrofuran, dioxane,1,2-dimethoxyethane and others), thus obtaining crystallized productsthat can be readily isolated and are easily purified. It proved to beespecially advantageous to add the desired base as early as during thecomplex formation to the reaction mixture and thereby to save a processstep.

In case the acidic complex compounds contain several free acidic groups,then it is often expedient to produce neutral mixed salts containinginorganic as well as organic cations as the counterions.

This can be done, for example, by reacting the complex-forming,acid inan aqueous suspension or solution with the oxide or salt of the elementyielding the central ion and with half the amount of an organic baserequired for neutralization, isolating the thus-formed complex salt,purifying same if desired, and then combining, for completeneutralization, with the required amount of inorganic base. The sequenceof base addition can also be reversed.

The conjugates of antibody and complex are dialyzed prior to in vivoutilization after incubation with a weak complexing agent, such as, forexample, sodium citrate, sodium ethylenediaminetetraacetic acid, inorder to remove weakly bound metal atoms.

In case of using complex compounds which contain radioisotopes, thesecan be produced in accordance with the methods disclosed in"Radiotracers for Medical Applications", vol. 1, CRC-Press, Boca Raton,Fla.

The pharmaceutical agents of this invention are produced in a likewiseconventional way by suspending or dissolving the complex compoundsaccording to this invention--optionally with admixture of the additivescustomary in galenic pharmacy--in an aqueous medium and subsequentlysterilizing the suspension or solution, if necessary. Suitable additivesare, for example, physiologically acceptable buffers (e.g.tromethamine), small additions of complexing agents (e.g.diethylenetriaminepentaacetic acid) or, if required, electrolytes, suchas, for example, sodium chloride or, if necessary, antioxidants, suchas, for example, ascorbic acid.

If, for enteral administration or other purposes, suspensions orsolutions of the media of this invention in water or physiologicalsaline solution are desirable, the media are mixed with one or severalof the auxiliary agent(s) customary in galenic pharmacy (for example,methylcellulose, lactose, mannitol) and/or tenside(s)(e.g. lecithins,"Tween", "Myrj") and/or aromatizing material(s) for flavor amelioration(for example ethereal oils).

In principle, it is also possible to produce the pharmaceuticals of thisinvention even without isolation of the Complex salts. In any event,special care must be taken to effect chelate formation so that the saltsand salt solutions of this invention are practically devoid ofuncomplexed, toxically active metal ions.

This can be ensured, for example, with the aid of color indicators, suchas xylenol orange using control titrations during the manufacturingprocess. Therefore, the invention also relates to processes forpreparing the complex compounds and their salts. The final safetymeasure available is a purification of the isolated complex salt.

The pharmaceutical agents of this invention preferably contain 1 μmol to1 mol/l of the complex salt and are normally provided in doses amountingto 0.001-5 mmol/kg. They are intended for enteral and parenteraladministration.

The complex compounds according to the invention are utilized

(1) for NMR and X-ray diagnostics in the form of their complexes withthe ions of the elements of atomic numbers 21-29, 42, 44 and 57-83;

(2) for radiodiagnostics and radiotherapy in the form of their complexeswith the radioisotopes of the elements of atomic numbers 27, 29, 31, 32,38, 39, 43, 49, 62, 64, 70 and 77.

The agents of this invention meet the variegated requirements for beingsuitable as contrast media for nucelar spin tomography. Thus, they areexcellently suited for improving the informative content of the imageobtained with the, aid of the nuclear spin tomograph upon oral orparenteral administration, by enhancing signal intensity. Furthermore,they exhibit the high efficacy necessary for burdening the body withminimum quantities of foreign substances, and they show the goodcompatibility required for maintaining the noninvasive character of theexaminations.

The good water solubility of the media according to this invention makesit possible to prepare highly concentrated solutions, thus maintainingthe volume load on the circulation within tolerable limits andcompensating for dilution by body fluids; in other words, NMR diagnosticmedia must have a water solubility that is 100 to 1000 times higher thanfor NMR spectroscopy. Furthermore, the media of this invention exhibitnot only high stability in vitro, but also a surprisingly high stabilityin vivo so that release or exchange of the ions--toxic per se--not boundin a covalent fashion in the complexes takes place only extremelygradually within the time period during which the novel contrast mediaare again completely eliminated.

In general, the media of this invention are utilized as NMR diagnosticagents in doses amounting to 0.001-5 mmol/kg, preferably 0.005-0.5mmol/kg. Details of use are discussed, for example, in H. J. Weinmann etal., Am. J. of Roentgenology 142: 619 (1984).

Especially low doses (below 1 mg/kg of body weight) of organ-specificNMR diagnostica are usable, for example, for the detection of tumors andof cardiac infarction.

The complex compounds of this invention can furthermore be utilized withadvantage as susceptibility reagents and as shift reagents for in vivoNMR spectroscopy.

The media of this invention are likewise suitable as radiodiagnosticagents based on their advantageous radioactive properties and the goodstability of the complex compounds contained therein. Details of theirusage and dosage can be derived, for example, from "Radiotracers forMedical Applications", CRC-Press, Boca Raton, Fla.

Another imaging method using radioisotopes is positron emissiontomography utilizing positron-emitting isotopes, such as, for example,⁴³ Sc, ⁴⁴ Sc, ⁵² Fe, ⁵⁵ Co and ⁶⁸ Ga. (Heiss, W. D., Phelps, M. E.,Positron Emission Tomography of Brain, Springer Publishers, Berlin,Heidelberg, New York 1983.)

The compounds of this invention can also be used in radioimmunotherapy.This procedure differs from the corresponding diagnostic method merelyin the amount and type of the radioactive isotope employed. Theobjective resides in destruction of tumor cells by high-energyshort-wave radiation with a minimum range. The specificity of theantibody utilized is of decisive importance herein since unspecificallylocalized antibody conjugates result in destruction of healthy tissue.

The antibody or antibody fragment of the antibody-metal complexaccording to this invention serves for transporting the compleximmune-specific for the respective antigen to the target organ where themetal ion, selected on account of its cell-killing properties, can emitradiation inflicting lethal damage to the cells. Suitable β-emittingions are, for example, ⁴⁶ Sc, ⁴⁷ Sc, ⁴⁸ Sc, ⁷² Ga and ⁷³ Ga. Examples ofα-emitting ions exhibiting suitable low half-life values are ²¹¹ Bi, ²¹²Bi, ²¹³ Bi and ²¹⁴ Bi, wherein ²¹² Bi is preferred. A suitable ionemitting photons and electrons is ¹⁵⁸ Gd which can be obtained byneutron capture from ¹⁵⁷ Gd.

In the in vivo administration of the therapeutic agents according tothis invention, they can be administered together with a suitableexcipient, such as, for example serum or physiological saline solutionand together with another protein, such as, for example, human serumalbumin. The dose herein depends on the type of cellular disorder, themetal ion employed, and the type of imaging method.

The therapeutic media of this invention are administered parenterally,preferably intravenously.

Details of the use of radiotherapeutic agents are discussed, forexample, in R. W. Kozak et al., TIBTEC, October 1986, 262.

The media according to the invention are excellently suited as X-raycontrast agents; in this connection, it is to be particularly emphasizedthat they reveal no traces of anaphylaxis-type reactions, known from theiodine-containing contrast media, in biochemical-pharmacological tests.They are of particular value, on account of favorable absorptioncharacteristics in the regions of higher tube voltages, for digitalsubtraction techniques.

In general, the media of this invention are used, for application asX-ray contrast media, in analogy to, for example, meglumine diatrizoate,in doses amounting to 0.1-5 mmol/kg, preferably 0.25-1 mmol/kg.

Details of utilization of X-ray contrast media are discussed, forexample, in Barke, "Rontgenkontrastmittel" X-Ray Contrast Media!, G.Thieme, Leipzig (1970) and P. Thurn, E. Bucheler--"Einfuhrung in dieRontgendiagnostik" Introduction to X-Ray Diagnostics!, G. Thieme,Stuttgart, New York (1977).

In summation, synthesis of novel complexing agents, metal complexes andmetal complex salts has been achieved opening up new possibilities indiagnostic and therapeutic medicine. This development appears to bedesirable, above all, in light of the evolution of novel imagingprocesses in medical diagnostics.

The compounds of general Formula I can also be utilized as haptens forthe production of antibodies. Details of the application of haptens tothe production of antibodies have been described, for example, in S.Sell, Immunology, Immunopathology and Immunity, 372, Harper and RowPubl., 3rd ed.

The examples set forth below serve for a more detailed explanation ofthe subject matter of this invention.

EXAMPLE 1 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)subericAcid Bis(tertbutyl)diester

15.31 g (0.064 mole) of 4-hydroxybenzyl-1,2-ethanediamine as thedihydrochloride and 71.14 g (0.71 mol) of potassium bicarbonate areprovided in 380 ml of dimethylformamide (dried over sodium hydride) and,at 35° C., 50 g (0.26 mol) of bromoacetio acid tert-butyl ester in 80 mlof dimethylformamide is added dropwise thereto. The mixture is stirredfor another 2.5 hours at 35° C., whereafter thin-layer chromatographyshows no longer any starting compound. The product is filtered off fromprecipitated potassium bromide and the filtrate is concentrated. Theresidue is combined with water and repeatedly extracted with ether.After drying and concentration, the ether extract is purified over asilica gel column from unreacted bromoacetic acid tert-butyl ester, thusobtaining 24.8 g (63% of theory) of a colorless oil.

Analysis

Calcd: C 63.64; H 8.73; N 4.49; O 23.12.

Found: C 63.78; H 8.69; N 4.41.

(b) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-benzyloxycarbonylaminopropoxy) benzyl!suberic AcidBis(tert-butyl)diester

1.0 g (1.61 millimoles) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)subericacid bis(tert-butyl)diester (Example 1a) is combined with 53 mg of NaH(80% strength in paraffin) (1.77 mmol) in 10 ml of dry tetrahydrofuran,and 440 mg of N-(3-bromopropyl)carbamic acid benzyl ester in 5 ml oftetrahydrofuran is gradually added dropwise to the reaction mixture.After agitation overnight, the mixture is concentrated and separatedfrom paraffin oil through a silica gel column. After evaporation of thesolvent, 920 mg (70.2% of theory) of a colorless oil is obtained.

Analysis

Calcd: C 64.92; H 8.29; N 5.16; O 21.61.

Found: C 64.99; H 8.20; N 5.07.

(c) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!suberic Acid Bis(tert-butyl)diester

0.92 g (1.13 mmol) of 3,6-diaza-3,6-bis(butoxycarbonylmethyl)-4-4-(3-benzyloxycarbonyl-aminopropoxy)benzyl!suberic acidbis(tert-butyl)diester (Example 1b)(1.13 mmol) is dissolved in 20 ml ofmethanol and hydrogenated with 500 mg of 10% palladium-carbon untilthere is no longer absorption of H₂. The mixture is then filtered offfrom the catalyst. The remaining colorless oil weighs 680 mg (74% oftheory).

Analysis

Calcd: C 63.59; H 9.04; N 6.18; O 21.17.

Found: C 63.43; H 8.99; N 6.15.

(d) 3,6-Diaza-3,6-bis (tert-butoxycarbonylmethyl)-4-4-(3(maleimido)propoxy)benzyl!suberic Acid Bis(tert-butyl)diester

6.5 g of 3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!suberic acid bis(tert-butyl)diester (Example1c)(9.4 mmol) in 200 ml of dry methylene chloride is combined with asolution of 920 mg (9.4 mmol) of maleic anhydride in 50 ml of methylenechloride and stirred overnight at room temperature. Then 1.27 g (9.4mmol) of 1-hydroxybenzotriazole and 2.13 g (10.34 mmol) ofdicyclohexylcarbodiimide are added. After 2 days, the mixture isfiltered off from separated urea and the product is purified bypreparative medium pressure chromatography (methylene chloride/ether).Yield: 3.89 g (80% of theory)

Analysis

Calcd: C 63.22; H 8.09; N 5.52; O 23.15.

Found: C 63.19; H 8.15; N 5.41.

(e) 3,6-Diaza-3,6-bis (carboxymethyl)-4- 4-(3-(maleimido)propoxy)benzyl!suberic Acid

2.4 g (9.2 mmol) of 3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-(maleimido)propoxy)-5 benzyl!suberic acid bis(tert-butyl)diester(Example 1d) is dissolved in 35 ml of trifluoroacetic acid and stirredfor 36 hours at room temperature. One-half of the trifluoroacetic acidis removed under vacuum and the remaining solution is poured into 100 mlof dry diethyl ether. The thus-precipitated product is suctioned off anddried, yielding 1.45 g (85%) of a white crystalline powder.

Melting point: >145° (decomposition)

Analysis

Calcd: C 53.82; H 5.45; N 7.84; O 32.86.

Found: C 53.89; H 5.41; N 7.85.

Gadolinium Complex

7.25 g (13.55 mmol) of 3,6-diaza-3,6-bis(carboxymethyl)-4-4-(3-(maleimido)propoxy)benzyl!suberic acid is dissolved in 120 ml of0.1N ammonium acetate/water and gradually combined with 14 ml of a 1Ngadolinium acetate solution in water. After 15 minutes the mixture isadjusted to a pH of about 7.5-8 with 0.1N ammonia solution, heated for15 minutes to 60° C., and then removed by centrifuging. The supernatantyields, after freeze-drying, 9.35 g of white crystalline mass (99% oftheory).

Analysis

Calcd: C 41.79; H 3.79; N 6.09; O 25.51 Gd 22.79.

Found: C 41.77; H 3.76; N 6.11; Gd 22.55.

Gd (atomic absorption spectroscopy=AAS): 22.72%

Sodium Salt of the Gadolinium Complex

The complex obtained as described above (3.63 g; 5.26 mmol) is dissolvedin ten times the amount of water and combined by means of amicro-burette with 5.26 ml of a 1N sodium hydroxide solution. Afterfreeze-drying, 3.74 g of white crystals is obtained.

Analysis

Calcd: C 40.44; H 3.67; N 5.89; O 24.69; Gd 22.06; Na 3.22.

Found: C 40.32; H 3.60; N 5.95; O; Gd 21.81; Na 3.33.

N-Methyl-D-glucamine Salt of the Gadolinium Complex

7.85 g (11.38 mmol) of the gadolinium complex dissolved in 80 ml ofwater is combined with 2.22 g (11.38 mmol) of N-methyl-D-glucamine underagitation, in incremental portions. After complete dissolution of thebase, the mixture is freeze-dried. There remains 10.0 g of a colorlesscrystalline compound.

Analysis

Calcd: C 42.07; H 4.89; N 6.53; O 28.92; Gd 17.76.

Found: C 42.12; H 4.77; N 6.59; O; Gd 17.77.

Morpholine Salt of the Gadolinium Complex

5.13 g (7.43 mmol) of the gadolinium complex dissolved in 50 ml of wateris combined with 6.4 g of a solution containing 10% by weight ofmorpholine and then freeze-dried, yielding 5.76 g of colorless crystals.

Analysis

Calcd: C 43.34; H 4.41; N 7.22; O 24.74; Gd 20.26.

Found: C 43.40; H 4.32; N 7.41; O; Gd 20.22.

Analogously to the directions for preparing the gadolinium complex, thefollowing are obtained:

Yttrium Complex

Calcd: C 46.31; H 4.21; N 6.75; O 28.28; Y 14.45.

Found: C 46.45; H 4.19; N 6.78; O; Y 14.07.

Ytterbium Complex

Calcd: C 40.86; H 3.71; N 5.96; O 24.95; Yb 24.53.

Found: C 40.83; H 3.81; N 5.87; O; Yb 24.41.

Samarium Complex

Calcd: C 42.21; H 3.84; N 6.16; O 25.77; Sm 22.02.

Found: C 42.17; H 3.82; N 6.05; O; Sm 22.13.

Praseodymium Complex

Calcd: C 42.81; H 3.89; N 6.24; O 26.14; Pr 20.92.

Found: C 42.18; H 3.79; N 6.22; O; Pr 20.97.

Cobalt Complex

Calcd: C 48.74; H 4.43; N 7.11; O 29.76; Co 9.96.

Found: C 48.73; H 4.71; N 7.33; O; Co 10.07.

Indium Complex

Calcd: C 44.53; H 4.05; N 49.31; O 27.19; In 17.74.

Found: C 44.56; H 3.98; N 49.27; In 17.82.

EXAMPLE 2 (a) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!suberic Acid Bis(tert-butyl)diester

7.33 g (10.6 mmol) of 3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!suberic acid bis(tert-butyl)diester (Example1c) dissolved in 175 ml of dry ethyl acetate is combined with 1.2 ml(11.7 mmol) of triethylamine and, at 0° C., a solution of 1.2 g (11mmol) of methacryloyl chloride in 20 ml of dry ethyl acetate is addeddropwise thereto. The mixture is stirred overnight at room temperature,then filtered off from precipitated triethylammonium chloride, andconcentrated. After column chromatography (toluene/ethyl acetate), 6.9 g(9.2 mmol; 87% of theory) of a colorless oil is obtained.

Analysis

Calcd: C 64.23; H 8.75; N 5.61 0.21.39.

Found: C 64.44; H 8.52; N 5.63

(b) 3,6-Diaza-3,6-bis(carboxymethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!suberic Acid

As described in Example 1e, 2.0 g (2.7 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!suberic acid bis(tert-butyl)diester(Example 2a) is converted with trifluoroacetic acid into the freecomplexing agent. After drying, 1.3 g (2.5 mmol; 92%) of a colorlesspowder is obtained.

Melting point: 133° C. (decomposition)

Analysis

Calcd: C 55.06; H 6.35; N 8.02; O 30.55.

Found: C 55.01; H 6.23; N 8.13.

Gadolinium Complex

In analogy to the directions in Example 1e, the gadolinium complex isobtained in almost quantitative yield.

Analysis

Calcd: C 42.53; H 4.46; N 6.19; O 23.6; Gd 23.20.

Found: C 42.38; H 4.30; N 6.25; Gd 23.02.

Gd (AAS): 23.25%.

Analogously to the directions in 1e, the following salts are obtained:

Sodium Salt of the Gadolinium Complex

Calcd: C 41.13; H 4.31; N 5.99; O 22.83; Gd 22.44; Na 3.28.

Found: C 41.20; H 4.39; N 5.89; O; Gd 21.99; Na 3.27.

Meglumine Salt of the Gadolinium Complex

Calcd: C 43.96; H 5.13; N 7.32; O 23.00; Gd 20.55.

Found: C 43.89; H 5.22; N 7.30; O; Gd 21.01.

Morpholine Salt of the Gadolinium Complex

Calcd: C 42.60; H 5.53; N 6.41; O 27.45; Gd 17.99.

Found: C 42.65; H 5.60; N 6.42; O; Gd 17.79.

EXAMPLE 3 (a)3,6-Diaza-3,6-bis(tert-butoxycaronylmethyl)-4-(4-benzyloxycarbonylmethoxybenzyl)subericAcid Bis(tert-butyl)diester

93.06 g of3,6-diaza-3,6-bis(tert-butoxy-carbonylmethyl)-4-(4-hydroxybenzyl)subericacid bis(tert-butyl)diester (Example 1a)(0.15 mol) is gradually combinedwith 4.48 g of NaH (80% in paraffin)(0.15 mol) in 600 ml of drytetrahydrofuran under agitation, and then, at room temperature, 34.4 gof bromoacetic acid benzyl ester (0.15 mol) in 150 ml of drytetrahydrofuran is added dropwise thereto. After agitation overnight,the mixture is suctioned off from precipitated sodium bromide,concentrated, taken up in diethyl ether, and the remaining inorganiccomponents are removed by washing with water. After drying with MgSO₄,the product is freed of solvent and purified over a silica gel column,thus obtaining 75.2 g (65% of theory) of a colorless oil.

Analysis

Calcd: C 65.43; H 8.10; N 3.63; O 22.82.

Found: C 65.23; H 8.17; N 3.58.

(b)3,6-Diaza-3,6-bis(carboxymethyl)-4-(4-benzyloxycarbonylmethoxybenzyl)subericAcid

5.49 g of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4benzyloxycarbonylmethoxybenzyl)subericacid bis(tert-butyl)diester (Example 3a) (8.1 mmol) is heated to 50° C.in 50 ml of trifluoroacetic acid and allowed to stand overnight at roomtemperature. Then the clear solution is poured into 500 ml of dry etherand the precipitate is suctioned off. After drying, 2.4 g of whitecrystals is obtained (54.5% of theory), decomposing with gas evolutionstarting at 150° C.

Analysis

Calcd: C 57.13; H 5.53; N 5.12; O 32.20.

Found: C 57.21; H 5.51; N 4.98.

The gadolinium complex is produced using the procedure described inExample 1e.

Analysis

Calcd: C 44.56; H 3.88; N 3.99; O 25.11; Gd 22.43.

Found: C 44.42; H 3.85; N 4.05; Gd 21.93.

Gd (AAS): 22.38%.

The following salts are likewise obtained pursuant to the processdisclosed in 1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 43.20; H 3.62; N 3.87; O 24.35; Gd 21.75; Na 3.18.

Found: C 43.14; H 3.66; N 3.85; O; Gd 21.15; Na 3.09.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.28; H 4.84; N 4.69; O 28.60; Gd 17.57.

Found: C 44.30; H 4.81; N 4.75; O; Gd 17.23.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.79; H 4.48; N 5.34; O 24.39; Gd 19.98.

Found: C 45.81; H 4.41; N 5.37; O; Gd 19.59.

EXAMPLE 4 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylmethoxybenzyl)subericAcid Bis(tert-butyl)diester

6.8 g of3,6-diaza-3,6-bis(tert-butoxycarbonyl-methyl)-4-(4-benzyloxycarbonylmethoxybenzyl)subericacid bis(tert-butyl)diester (Example 3a)(8.82 mmol) dissolved in 25 mlof absolute ethanol is added dropwise to a solution of 1.1 ml ofhydrazine hydrate (22.3 mmol) in 50 ml of ethanol at 5° C.-10° C. andstirred overnight at room temperature. Then the mixture is concentratedto half the amount, poured into 400 ml of H₂ O and repeatedly extractedwith ether. After drying and evaporation of the organic phase, theproduct is purified via a silica gel column, thus obtaining 5.85 g(95.4% of theory) of a colorless oil.

Analysis

Calcd: C 60.49; H 8.41; N 8.06; O 23.02.

Found: C 60.60; H 8.31; N 8.07.

(b)3,6-Diaza-3,6-bis(carboxymethyl)-4-(4-hydrazinocarbonylmethoxybenzyl)subericAcid

7.7 g (10.9 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylmethoxy-benzyl)subericacid bis(tert-butyl)diester (Example 4a) is allowed to stand in 80 ml oftrifluoroacetic acid for 2 hours at room temperature. Then the mixtureis poured into dry ether and decanted. Thereafter, the mixture isstirred for another half hour with 100 ml of a 10% ether-triethylaminesolution, suctioned off, and dried under vacuum: 4.5 g of whitecrystals, melting point 185° C. (decomposition). Yield: 4.5 g (89% oftheory).

Analysis

Calcd: C 48.50; H 5.57; N 11.90; O 34.0.

Found: C 48.27; H 5.56; N 11.93.

The gadolinium complex is prepared according to the procedure describedin Example 1e.

Analysis

Calcd: C 36.53; H 3.71; N 8.96; O 25.61; Gd 25.17.

Found: C 36.60; H 3.68; N 8.89; Gd 24.51.

Gd (AAS): 25.26%.

The following salts are obtained analogously to the directions inExample 1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 35.29; H 3.42; N 8.66; O 24.74; Gd 24.31; Na 3.55.

Found: C 35.33; H 3.40; N 8.71; O; Gd 24.01; Na 3.59.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 38.08; H 4.91; N 8.54; O 29.27; Gd 19.17.

Found: C 38.12; H 4.90; N 8.49; O; Gd 19.20.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 38.86; H 4.39; N 9.85; O 24.76; Gd 22.12.

Found: C 38.82; H 4.48; N 9.89; O; Gd 22.16.

EXAMPLE 5 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)subericAcid Bis(tert-butyl)diester

According to the directions given for Example 3a, 3.5 g (5.6 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)subericacid bis(tert-butyl)diester (Example 1a) and 1.6 g (5.6 mmol) of6-bromocaproic acid benzyl ester yield 3.6 g (78% of theory) of acolorless oil.

Analysis

Calcd: C 66.80; H 8.53; N 3.38; O 21.27.

Found: C 66.72; H 8.49; N 3.40.

(b)3,6-Diaza-3,6-bis(carboxymethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)subericAcid

In accordance with the directions given for Example 3b, 12.3 g (14.8mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)subericacid bis(tert-butyl)diester (Example 5a) yields 8.25 g (92% of theory)of a white crystallized product.

Melting point: 188° C. (decomposition)

Analysis

Calcd: C 59.79; H 6.35; N 4.64; O 29.20.

Found: C 55.92; H 6.41; N 4.74.

Gadolinium Complex

In accordance with the procedure disclosed in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 47.60; H 4.66; N 3.70; O 23.25; Gd 20.77.

Found: C 47.38; H 4.67; N 3.52; Gd 20.65.

The following salts are obtained analogously to the directions given inExample 1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 46.26; H 4.40; N 3.59; O 22.29; Gd 20.19; Na 2.95.

Found: C 46.25; H 4.36; N 3.60; O; Gd 20.09; Na 2.99.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 47.47; H 5.59; N 4.48; O 25.63; Gd 16.79.

Found: C 47.39; H 5.57; N 4.49; O; Gd 16.63.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 48.44; H 5.14; N 4.98; O 22.77; Gd 18.65.

Found: C 48.38; H 5.17; N 4.93; O; Gd 18.37.

EXAMPLE 6 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)subericAcid Bis(tert-butyl)diester

In accordance with the directions indicated for Example 4a, 6.35 g (7.68mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)subericacid bis(tert-butyl)diester (Example 5a) yields 5.07 g (88% of theory)of a colorless oil.

Analyse

Calcd: C 62.37; H 8.85; N 7.46; O 21.30.

Found: C 62.28; H 8.84; N 7.51.

(b)3,6-Diaza-3,6-bis(carboxymethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)subericAcid

According to the directions given for Example 4b, 2.66 g 13.54 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)subericacid bis(tert-butyl)diester (Example 6a) yields 1.69 g (91% of theory)of a white crystallized product.

Melting point: 210° C. (decomposition).

Analysis

Calcd: C 52.46; H 6.50; N 10.64; O 30.38.

Found: C 52.51; H 6.39; N 10.70.

Gadolinium Complex

In accordance with the procedure described in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 40.57; H 4.59; N 8.22; O 23.50; Gd 23.09.

Found: C 40.60; H 4.52; N 8.21; Gd 23.0.

The following salts are obtained analogously to the directions in 1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.31; H 4.30; N 7.97; O 22.76; Gd 22.37; Na 3.27.

Found: C 39.26; H 4.31; N 7.90; O; Gd 21.97; Na 3.27.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.13; H 5.52; N 7.99; O 27.39; Gd 17.95.

Found: C 41.20; H 5.55; N 7.87; O; Gd 17.81.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.28; H 5.12; N 9.13; O 22.94; Gd 20.50.

Found: C 42.31; H 5.07; N 9.14; O; Gd 20.11.

EXAMPLE 7 (a) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!suberic AcidBis(tert-butyl)diester

4.17 g (5.56 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)subericacid bis(tert-butyl)diester (Example 6a) is dissolved in 50 ml of drydichloromethane and combined with 0.6 ml of triethylamine. Then, at 0°C., a solution of 0.6 g of methacryloyl chloride in 10 ml ofdichloromethane is added, the mixture is stirred overnight at roomtemperature, and precipitated triethylammonium chloride is removed byfiltration. After filtering over silica gel with ethyl acetate, 3.14 g(69% of theory) of a colorless oil is obtained after evaporation of thesolvent.

Analysis

Calcd: C 63.05; H 8.61; N 6.84; O 21.48.

Found: C 62.98; H 8.70; N 6.82.

(b) 3,6-Diaza-3,6-bis(carboxymethyl)-4-4-(methacryloyl)-hydrazinocarbonylpentamethylenoxybenzyl!suberic Acid

In accordance with the directions set forth for Example 3b, 3.0 g (3.66mmol) of 3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(methacryloyl)-hydrazinocarbonylpentamethylenoxybenzyl!suberic acidbis(tert-butyl)diester (Example 7a) yields 1.92 g (88% of theory) of awhite crystallized product.

Melting point: 135° C. (decomposition).

Analysis

Calcd: C 54.53; H 6.44; N 9.42; O 29.59.

Found: C 54.60; H 6.13; N 9.51.

Gadolinium Conmplex

According to the process described in Example 1e, the gadolinium complexis obtained in an almost quantitative yield.

Analysis

Calcd: C 43.30; H 4.71; N 7.48; O 23.50; Gd 20.99.

Found: C 43.24; H 4.69; N 7.43; Gd 21.20.

Analogously to direction 1e, the following salts are obtained:

Sodium Salt of the Gadolinium complex

Analysis

Calcd: C 42.01; H 4.57; N 7.25; O 22.80; Gd 20.37; Na 2.97.

Found: C 41.96; H 4.55; N 7.30; O; Gd 20.03; Na 3.01.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.21; H 5.65; N 7.41; O 27.08; Gd 16.63.

Found: C 43.20; H 5.70; N 7.38; O; Gd 16.33.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.54; H 5.30; N 8.37; O 22.96; Gd 18.81.

Found: C 44.45; H 5.38; N 8.34; O; Gd 18.80.

EXAMPLE 8 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)subericAcid Bis(tert-butyl)diester

9.5 g of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylmethoxybenzyl)subericacid bis(tert-butyl)diester (Example 3a)(0.012 mol) is dissolved in 100ml of anhydrous tetrahydrofuran and hydrogenated in the presence of 2 gof 10% Pd/C until there is no longer any hydrogen absorption. After themixture has been suctioned off, the solvent is removed using a rotaryevaporator and the compound is further dried at 0.01 torr. The resultantviscous oil weighs 8.33 g (99% of theory).

Analysis

Calcd: C 61.74; H 8.29; N 4.11; O 25.84.

Found: C 61.82; H 8.17; N 4.12.

(b) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4- 4-(2,3,4,5,6-pentahydroxyhexyl)methylamino!carbonylmethoxybenzyl!subericAcid Bis(tert-butyl)diester

1.36 g of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)subericacid bis(tert-butyl)diester is dissolved in 50 ml of tetrahydrofuran andcombined with 0.3 g (3 mmol) of triethylamine. At -5° C., 0.29 g (2.02mmol) of chloroformic acid isobutyl ester in 20 ml of tetrahydrofuran isgently added and finally the mixture is combined with 5 ml of an aqueoussolution of 430 mg (2.2 mmol) of N-methyl-D-glucamine. After 30 minutesof agitation at 0° C., the cooling bath is removed and the mixture isallowed to warm up to room temperature. After evaporation of thesolvent, the residue is purified by chromatography on silica gel, thusobtaining 1.43 g of a white crystalline compound (83% of theory)decomposing under brown discoloration starting with 52° C.

Analysis

Calcd: C 58.79; H 8.34; N 4.89; O 27.96.

Found: C 58.62; H 8.32; N 4.79.

(c) 3,6-Diaza-3,6-bis(carboxymethyl)-4- 4-(2,3,4,5,6-pentahydroxyhexyl)methylamino!carbonylmethoxybenzyl!subericAcid

As described in Example 1e, 0.78 g (0.91 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4- 4-(2,3,4,5,6-pentahydroxyhexyl)methylamino!carbonylmethoxybenzyl!subericacid bis(tert-butyl)diester yields 432 mg (75% of theory) of the titlecompound, melting point 132° (decomposition).

Analysis

Calcd: C 49.28; H 6.20; N 6.63; O 37.87.

Found: C 49.19; H 6.21; N 6.46.

Gadolinium Complex

The gadolinium complex is obtained in an almost quantitative yieldanalogously to the directions in 1e:

Analysis

Calcd: C 39.36; H 4.6; N 5.33; O 30.46; Gd 19.95.

Found: C 39.72; H 4.66; N 5.32; Gd 19.75.

Gd (AAS): 20.01% by weight.

Analogously to the directions of 1e, the following compounds arelikewise obtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 38.56; H 4.35; N 5.18; O 29.63; Gd 19.41; Na 2.83.

Found: C 38.50; H 4.34; N 5.09; Gd 19.50; Na 2.81.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 40.31; H 5.43; N 5.69; O 32.55; Gd 15.99.

Found: C 40.29; H 5.40; N 5.67; Gd 15.80.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.23; H 5.07; N 6.41; O 29.29; Gd 17.99.

Found: C 41.20; H 4.98; N 6.37; Gd 17.69.

EXAMPLE 9 (a) O-Benzyl-N-trifluoroacetyltyrosine

112.5 g (0.41 mmol) of O-benzyltyrosine is suspended in 1 liter of drymethanol and combined at room temperature with 58.9 ml (0.42 mol) oftriethylamine. After adding 67 ml (0.53 mol) of trifluoroacetic acidethyl ester, the mixture is stirred at room temperature for 130 hoursunder exclusion of moisture. The mixture is separated from unreactedstarting material and volatile components are removed by shaking withethyl acetate/aqueous hydrochloric acid. The ethyl acetate phase isdecolorized with activated carbon. Evaporation of the solvents yields120.7 g (80% of theory) of colorless crystals.

Melting point: 149°-150° C.

Analysis

Calcd: C 58.85; H 4.39; N 3.81; O 17.42; F 15.51.

Found: C 58.78; H 4.29; N 3.79; F 15.57.

(b) O-Benzyl-N-trifluoroacetyltyrosine-(2-carbobenzoxyaminoethylen)amide

18.5 g (50.4 mmol) of O-benzyl-N-trifluoro-acetyltyrosine (Example 9a)is dissolved in 200 ml of dry tetrahydrofuran, combined with 7 ml ofEt3N, and then 4.8 ml (50.8 mmol) of chloroformic acid ethyl ester isadded dropwise while maintaining the temperature at below -10° C. Afterthis adding step is completed, the mixture is agitated for 30 minutes atthis temperature, again combined with the same amount of precooledtriethylamine, and an ice-cold solution of 11.6 g (50.4 mmol) ofN-(2-aminoethyl)carbamic acid benzyl ester hydrochloride in 100 ml ofdimethylformamide is added dropwise. The mixture is stirred for another30 minutes at -10° C., then allowed to warm up to room temperature underagitation, and thereafter heated for 10 minutes to 30° C. Then thesolvent is removed by rotary evaporator and the mixture poured on 750 mlof ice water. The crystallized product is suctioned off, washed with icewater, and dried. The yield is 26.9 g (94% of theory).

Melting point: 189°-190° C.

Analysis

Calcd: C 61.87; H 5.19; N 7.73; O 14.71; F 10.48.

Found: C 61.90; H 5.08; N 7.77; F 10.43.

(c) O-Benzyltyrosine-(2-carbobenzoxyaminoethylen)amide

25.9 g (47.8 mmol) ofO-benzyl-N-trifluoroacetyltyrosine-(2-carbobenzoxyaminoethylen)amide(Example 9b) is suspended in 300 ml of EtOH and combined in portionswith 7.2 g (191 mmol) of sodium borohydride. After agitation overnightat room temperature, the mixture is combined with 50 ml of acetone,freed of solvent, mixed with 500 ml of H₂ O, and repeatedly extractedwith ethyl acetate. The organic phase yields, after drying andconcentration, 18.8 g (88% of theory) of white crystals, melting point145° C.

Analysis

Calcd: C 69.77; H 6.53; N 9.38; O 14.29.

Found: C 69.79; H 6.53; N 9.35.

(d) Tyrosine-(2-aminoethylen) amide

42.3 g (94.6 mmol) of O-benzyltyrosine-(2-carbobenzoxyaminoethylen)amide(Example 9c) is dissolved in 1.1 liter of methanol, 2 g of 10%palladium-carbon is added, and the mixture is hydrogenated underagitation until hydrogen absorption has ceased. The catalyst is filteredoff and the solvent evaporated. The mixture is dissolved in methanolunder heating and precipitated with ether: 17 g (86% of theory) ofcolorless crystals.

Melting point: 138°-141° C.

Analysis

Calcd: C 59.17; H 7.67; N 18.81; O 14.33.

Found: C 59.23; H 7.51; N 18.90.

(e) 3-Aza-l-(4-hydroxybenzyl)pentane-l,5-diamine•Trihydrochloride

6.55 g (29.3 mmol) of tyrosine-(2-amino-ethylen)amide (Example 9d) issuspended in 130 ml of dry tetrahydrofuran, and a gradual stream of B₂H₆ (from 5.8 g of NaBH₄ in 75 ml of diethylene glycol dimethyl etherand. 54 ml of boron trifluoride etherate complex) is passed with drynitrogen under continuous agitation through the solution. The mixture isstirred overnight at 60° C., then at 20° C. 30 ml of methanol is addeddropwise and, under ice cooling, hydrogen chloride is introduced. Thenthe mixture is briefly boiled and suctioned off. The trihydrochloride isobtained in the form of colorless crystals (8.04 g; 86% of theory).

Melting point: 250° C. (decomposition)

Analysis

Calcd: C 41.45; H 6.95; N 13.18; O 5.02; Cl 33.37.

Found: C 41.37; H 6.89; N 13.14; Cl 33.51.

(f)3,6,9-Triaza-4-(4-hydroxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicAcid Bis(tert-butyl)diester

2.07 g (6.5 mmol) of3-aza-1-(4-hydroxybenzyl)pentane-1,5-diamine•trihydrochloride (Example9e) is produced with 5.2 g of sodium bicarbonate and 6.34 g (82.2 mmol)of bromoacetic acid tert-butyl ester according to the directions for3,6-diaza-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)suberic acidbis(tert-butyl)diester (Example 1a), thus obtaining 3.54 g (68.8% of acolorless oil.

Analysis

Calcd: C 63.13; H 8.91; N 5.38; O 22.56.

Found: C 63.21; H 8.90; N 5.42.

(g) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonyl-methyl)-4-4-(3-benzyloxycarbonylaminopropoxy)benzyl!undecanedioic AcidBis(tert-butyl)diester

From 4.6 g (5.90 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 9f), following the directionsindicated for Example 1b, 4.2 g of a colorless oil (yield 74% of theory)is obtained.

Analysis

Calcd: C 64.30; H 8.51; N 5.76; O 21.41.

Found: C 64.20; H 8.65; N 5.82.

(h) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

In accordance with the method described in Example 1c, 3.9 g (4.8 mmol)of 3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-benzyloxycarbonylaminopropoxy)benzyl!undecanedioic acidbis(tert-butyl)diester (Example 9g) is hydrogenated. A colorless,viscous oil is obtained. Yield: 3.17 g (97.3% of theory).

Analysis

Calcd: C 63.13; H 9.15; N 6.69; O 21.02.

Found: C 62.97; H 9.01; N 6.62.

(i) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-(maleimido)propoxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

In accordance with the procedure described in Example 1d, the maleimideis obtained in a 91% yield (colorless, viscous oil), starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example 9h).

Analysis

Calcd: C 62.86; H 8.35; N 6.10; O 22.62.

Found: C 62.71; H 8.33; N 6.10.

(j) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-4-(3-(maleimido)propoxy)benzyl!undecanedioic Acid

As disclosed in Example 1e, the free penta acid is obtained in an 89%yield, starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)i4-4-(3-(maleimido)propoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example 9i), as a white powder.

Melting point: >161° C. (decomposition).

Analysis

Calcd: C 52.82; H 5.69; N 8.80; O 32.67.

Found: C 52.72; H 5.63; N 8.86.

Gadolinium Complex

Analysis of the description in Example 1e, the gadolinium complex isobtained in an almost quantitative yield.

Analysis

Calcd: C 42.52; H 4.20; N 7.08; O 26.30; Gd 19.88.

Found: C 42.58; H 4.29; N 7.83; O; Gd 19.89.

Gd (AAS): 19.73%.

As described in 1e, the following salts are obtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 40.28; H 3.74; N 6.71; O 24.91; Gd 18.83; Na 5.50.

Found: C 40.23; H 3.77; N 6.90; O; Gd 18.58; Na 5.47.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.70; H 5.85; N 7.28; O 30.52; Gd 13.63.

Found: C 42.58; H 5.69; N 7.35; Gd 13.51.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.89; H 5.12; N 8.72; O 24.91; Gd 16.32.

Found: C 44.93; H 5.15; N 8.77; Gd 16.15.

In analogy to the direction for preparing the gadolinium complex, thefollowing are obtained:

Indium Complex

Calcd: C 44.93; H 4.44; N 7.49; O 27.79; In 15.34.

Found: C 44.94; H 4.61; N 7.44; In 15.32.

Yttrium Complex

Calcd: C 46.48; H 4.59; N 7.75; O 28.75; Y 12.43.

Found: C 46.50; H 4.62; N 7.61; Y 12.45.

Ytterbium Complex

Calcd: C 41.68; H 4.12; N 6.95; O 25.79; Yb 21.45.

Found: C 41.55; H 4.17; N 6.81; Yb 21.32.

Samarium Complex

Calcd: C 42.89; H 4.24; N 7.15; O 26.53; Sm 19.18.

Found: C 42.81; H 4.23; N 7.20; Sm 19.31.

Praseodymium Complex

Calcd: C 43.42; H 4.29; N 7.24; O 26.86; Pr 18.19.

Found: C 43.32; H 4.43; N 7.31; Pr 18.20.

Cobalt Complex

Calcd: C 48.56; H 4.80; N 8.09; O 30.04; Co 8.51.

Found: C 48.58; H 4.73; N 8.18; Co 8.36.

EXAMPLE 10 (a)3,6,9-Triaza-4-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicAcid Bis(tert-butyl)diester

In accordance with the directions given in Example 3a, 1.98 g (2.54mmol) of3,6,9-triaza-4-(4-hydroxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) and 0.54 g of bromoacetic acidbenzyl ester (2.54 mmol) yield 1.35 g (1.45 mmol) of a colorless syrup(62% of theory).

Analysis

Calcd: C 64.70; H 8.36; N 4.52; O 22.4

Found: C 64.91; H 8.31; N 4.55

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-(4-benzyloxycarbonylmethoxybenzyl)undecanedioicAcid

According to the directions given in Example 3b, 5.3 g (5.71 mmol) of3,6,9-triaza-4-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example10a) yields 3g (82% of theory) of awhite solid.

Melting point: 145° C. (decomposition).

Analysis

Calcd: C 55.63; H 5.75; N 6.48; O 32.11.

Found: C 55.69; H 5.70; N 6.43.

The gadolinium complex was prepared in accordance with the proceduredisclosed in Example 1e.

Analysis

Calcd: C 44.93; H 4.27; N 5.24; O 25.93; Gd 19.61.

Found: C 44.87; H 4.14; N 5.30; Gd 19.41.

Gd (AAS): 19.62%.

The following salts are obtained by following the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 42.60; H 3.81; N 4.96; O 24.59; Gd 18.59; Na 5.43.

Found: C 42.54; H 3.87; N 4.99; Gd 18.38; Na 5.47.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.32; H 5.74; N 5.87; O 30.86; Gd 13.18.

Found: C 44.50; H 5.65; N 5.88; Gd 13.07.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 46.85; H 5.17; N 7.18; O 24.63; Gd 16.14.

Found: C 46.57; H 5.15; N 7.25; Gd 15.97.

EXAMPLE 11 (a)3,6,9-Triaza-4-(4-hydrazinocarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicAcid Bis(tert-butyl)diester

In accordance with the directions given in Example 4a, 12.6 g (13.57mmol) of3,6,9-triaza-4-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 10a) yields 9.6 g (83% of theory)of a colorless oil which is highly viscous at room temperature.

Analysis

Calcd: C 60.61; H 8.63; N 8.21; O 22.53.

Found: C 60.47; H 8.70; N 8.12.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-(4-hydrazinocarbonylmethoxybenzyl)undecanedioicAcid

6.8 g (7.9 mmol) of3,6,9-triaza-4-(4-hydrazinocarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example a) is reacted with trifluoroaceticacid according to the directions in Example 4b. After the reactionmixture has been worked up, 3.1 g of white crystals is obtained (67% oftheory).

Melting point: 180° C. (decomposition).

Analysis

Calcd: C 48.33; H 5.81; N 12.25; O 33.59.

Found: C 48.46; H 5.79; N 12.30.

The gadolinium complex was prepared according to the procedure describedin Example 8

Analysis

Calcd: C 33.06; H 4.16; N 9.64; O 26.45; Gd 21.66.

Found: C 32.98; H 4.08; N 9.55; Gd 21.03.

Gd (AAS): 21.57%.

The following salts are obtained in analogy to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 35.88; H 3.66; N 9.09; O 24.94; Gd 20.42; Na 5.97.

Found: C 35.78; H 3.57; N 9.00; Gd 20.23; Na 5.96.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 39.85; H 5.69; N 8.79; O 31.56; Gd 14.10.

Found: C 39.81; H 5.70; N 8.73; Gd 14.00.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.46; H 5.16; N 10.91; O 24.94; Gd 17.51.

Found: C 41.41; H 5.17; N 10.99; Gd 17.48.

EXAMPLE 12 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

In accordance with the directions given for Example 3a, 7.3 g (9.36mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) and 2.67 g (9.36 mmol) of6-bromocaproic acid benzyl ester yield 7.19 g (78% of theory) of acolorless oil.

Analysis

Calcd: C 65.89; H 8.70; N 4.26; O 21.13.

Found: C 65.76; H 8.62; N 4.30.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicAcid

According to the directions given for Example 3b, 6.93 g (7.04 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) yields 4.30 g (87% of theory) ofa white crystallized product.

Melting point: 173° C. (decomposition).

Analysis

Calcd: C 58.02; H 6.44; N 5.97; O 29.55.

Found: C 58.02; H 6.34; N 5.96.

Gadolinium Complex

In accordance with the procedure disclosed in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 47.59; H 4.93; N 4.89; O 24.24; Gd 18.32.

Found: C 47.50; H 4.83; N 4.98; Gd 18.22.

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 45.27; H 4.47; N 4.65; O 23.06; Gd 17.43; Na 5.09.

Found: C 45.33; H 4.45; N 4.61; Gd 17.51; Na 5.11.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 46.18; H 6.13; N 5.60; O 29.47; Gd 12.59.

Found: C 46.17; H 6.14; N 5.51; Gd 12.61.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 48.96; H 5.67; N 6.79; O 23.29; Gd 15.26.

Found: C 48.99; H 5.61; N 6.78; Gd 15.17.

EXAMPLE 13 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

According to the directions given in Example 4a, 16.35 g (16.61 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 12a) yields 14.03 g (93% of theory)of a colorless oil.

Analysis

Calcd: C 62.15; H 8.99; N 7.71; O 21.14.

Found: C 62.01; H 8.72; N 7.78.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicAcid

According to the directions set forth for Example 4b, 6.25 g (6.88 mmol)of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) yields 3.86 g (87% of theory) ofa white crystallized product.

Melting point: 225° C. (decomposition).

Analysis

Calcd: C 51.66; H 6.58; N 11.15; O 30.58.

Found: C 51.52; H 6.57; N 11.20.

Gadolinium Complex

According to the procedure described in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 41.47; H 4.89; N 8.95; O 24.55; Gd 20.11.

Found: C 41.41; H 4.90; N 9.01; Gd 20.12.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.26; H 4.39; N 8.48; O 23.24; Gd 19.04; Na 5.56.

Found: C 39.18; H 4.33; N 8.40; Gd 19.00; Na 5.53.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.00; H 6.19; N 8.36; O 30.02; Gd 13.41.

Found: C 42.10; H 6.15; N 8.33; Gd 13.20.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.06; H 5.70; N 10.27; O 23.47; Gd 16.48.

Found: C 43.95; H 5.71; N 10.23; Gd 16.42.

EXAMPLE 14 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!undecanedioicAcid Bis(tert-butyl)diester

In accordance with the directions given for Example 7a, 7.78 g (8.56mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 13a) yields 6.02 g (72% of theory)of a colorless oil.

Analysis

Calcd: C 62.74; H 8.77; N 7.17; O 21.3.

Found: C 62.51; H 8.80; N 7.20.

(b) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!undecanedioicAcid

According to the procedure given for Example 3b, 1.98 g (2.02 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!undecanedioicacid bis(tert-butyl)diester (Example a) yields 1.38 g (98% of theory) ofa white crystallized product.

Melting point: 162° C. (decomposition).

Analysis

Calcd: C 53.51; H 6.51; N 10.06; O 29.89.

Found: C 53.60; H 6.72; N 10.10.

Gadolinium Complex

In accordance with the process disclosed in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 43.80; H 4.98; N 8.23; O 24.47; Gd 18.50.

Found: C 43.71; H 4.81; N 8.09; Gd 18.41.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 41.60; H 4.61; N 7.82; O 23.24; Gd 17.57; Na 5.13.

Found: C 41.55; H 4.62; N 7.78; Gd 17.50; Na 5.12.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.53; H 6.25; N 7.89; O 29.64; Gd 12.66.

Found: C 43.49; H 6.27; N 7.87; Gd 12.51.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.78; H 5.81; N 9.58; O 23.45; Gd 15.36.

Found: C 45.77; H 5.80; N 9.53; Gd 15.31.

EXAMPLE 15 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic AcidBis(tert-butyl)diester

In accordance with the method described in Example 2a, starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example 9h), the title compound is obtained in an 89% yield.

Analysis

Calcd: C 63.69; H 8.90; N 6.18; O 21.21.

Found: C 63.61; H 8.71; N 6.22.

(b) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic Acid

According to the directions set forth for Example 2b, starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic acidbis(tert-butyl)diester (Example a), the title compound is obtained in a90% yield.

Analysis

Calcd: C 53.83; H 6.45; N 8.96; O 30.73.

Found: C 53.75; H 6.25; N 8.90.

Gadolinium Complex

According to the procedure described in Example 1e, the gadoliniumcomplex is obtained in a 98% yield.

Analysis

Calcd: C 43.17; H 4.78; N 7.19; O 24.65; Gd 20.18.

Found: C 43.30; H 4.70; N 7.17; Gd 20.22.

Gd (AAS): 20.25%.

The following salts are obtained in analogy to the method describedin1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 40.87; H 4.28; N 6.80; O 23.33; Gd 19.11; Na 5.58.

Found: C 40.85; H 4.23; N 6.74; Gd 19.01; Na 5.55.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.10; H 6.20; N 7.18; O 30.07; Gd 13.43.

Found: C 41.15; H 6.19; N 7.20; Gd 13.28.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.41; H 5.71; N 8.82; O 23.52; Gd 16.51.

Found: C 45.36; H 5.84; N 8.78; Gd 16.39.

EXAMPLE 16 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

In accordance with the method set forth in Example 8a, 7.83 g (8.43mmol) of3,6,9-triaza-4-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 10a) yields 4.2 g of a colorlessoil (yield 74% of theory).

Analysis

Calcd: C 61.62; H 8.53; N 5.01; O 24.81.

Found: C 61.73; H 8.53; N 5.10.

(b) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(2,3,4,5,6-pentahydroxyhexyl)methylaminocarbonylmethoxybenzyl!undecanedioicAcid Bis(tert-butyl)diester

4.56 g (5.4 mmol) of3,6,9-triaza-3,6,9-tris-(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)undecanedioicacid bis(tert-butyl)diester is dissolved in 100 ml of tetrahydrofuranand combined with 0.5 g (8 mmol) of triethylamine. At -5° C., 0.73 g(5.5 mmol) of chloroformic acid isobutyl ester in 40 ml oftetrahydrofuran is gently added and finally the mixture is combined with10 ml of an aqueous solution of 1.08 g (5.5 mmol) ofN-methyl-D-glucamine. After 30 minutes of agitation at 0° C., thecooling bath is removed and the mixture allowed to warm up to roomtemperature. After evaporation of the solvent, the residue is purifiedby chromatography on silica gel, thus obtaining 4.17 g of white,crystalline compound (76% of theory) decomposing with browndiscoloration starting with 50° C.

Analysis

Calcd: C 59.15; H 8.53; N 5.51; O 26.79.

Found: C 59.07; H 8.56; N 5.50.

(c) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-4-(2,3,4,5,6-pentahydroxyhexyl)methylaminocarbonylmethoxybenzyl!undecanedioicAcid

As described in Example 1e, 3.25 g (3.2 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(2,3,4,5,6-pentahydroxyhexyl)methylaminocarbonylmethoxybenzyl!undecanedioicacid bis(tert-butyl)diester yields 1.86 g (79% of theory) of the titlecompound having a melting point of 132° C. (decomposition).

Analysis

Calcd: C 49.04; H 6.31; N 7.62; O 37.01.

Found: C 49.19; H 6.21; N 7.46.

Gadolinium Complex

Analogously to the directions in 1e, the gadolinium complex is obtainedin an almost quantitative yield:

Analysis

Calcd: C 40.53; H 4.87; N 6.30; O 30.59; Gd 17.68.

Found: C 40.72; H 4.65; N 6.32; Gd 17.75.

Gd (AAS): 17.51% by weight.

The following salts are obtained in analogy to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 38.62; H 4.42; N 6.00; O 29.15; Gd 16.85; Na 4.92.

Found: C 38.68; H 4.48; N 5.93; Gd 16.54; Na 4.98.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.30; H 6.06; N 6.56; O 33.76; Gd 12.29.

Found: C 41.27; H 5.98; N 6.69; Gd 11.90.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.01; H 5.60; N 7.91; O 28.64; Gd 14.81.

Found: C 43.06; H 5.62; N 7.98; Gd 14.88.

EXAMPLE 17 (a) 3-Aza-2-(4-benzyloxybenzyl)-4-oxoglutaric Acid Diamide(Method A)

3.62 g (13.3 mmol) of O-benzyltyrosinamide is refluxed with 2.7 g ofethyl oxamate (23 mmol) for 14 hours in dimethoxyethane. Afterevaporation of the solvent, the mixture is washed in succession withwater, ethanol, and ether. After drying, 2.73 g of white crystals (60%of theory) is obtained.

Melting point: 270° C.

Analysis

Calcd: C 63.33; H 5.61; N 12.30; O 18.74.

Found: C 63.24; H 5.52; N 12.14.

or, according to Method B:

(α) 3-Aza-2-(4-benzyloxybenzyl)-4-oxoglutaric Acid 5-Ethyl Ester 1-Amide

3 g (11.1 mmol) of O-benzyltyrosinamide is dissolved in 30 ml ofdimethoxyethane, combined with 1.56 ml of triethylamine, and, at 0° C.,1.53 g (11.1 mmol) of oxalic acid ethyl ester chloride is added dropwisethereto. After 30 minutes at 0° C., the mixture is poured on 100 ml ofice, suctioned off, and dried. The yield is 3.87 g (94% of theory).

Melting point: 142° C.

Analysis

Calcd: C 64.85; H 5.98; N 7.56; O 21.59.

Found: C 64.71; H 6.11; N 7.46.

(β) 3.6 g (9.72 mmol) of 3-aza-2-(4-benzyloxybenzyl)-4-oxoglutaric acid5-ethyl ester 1-amide (Example aα) is covered by 40 ml of a solution of1 mole of NH₃ /l of methanol by pouring the solution thereover. After 1hour, the thus-precipitated product is filtered off. After drying, 3.13g (95% of theory) of the title compound is obtained in the form ofcolorless crystals.

Melting point: 269° C.

Analysis

Calcd: C 63.33; H 5.61; N 12.30; O 18.74.

Found: C 63.25; H 5.63; N 12.17.

(b) 3 -Aza-2 -(4 -hydroxybenzyl)-4 -oxoglutaric Acid Diamide

One gram (2.9 mmol) of 3-aza-2-(4-benzyloxybenzyl)-4-oxoglutaric aciddiamide (Example a) is suspended in 20 ml of methanol with 100 mg of 10%palladium-carbon and several drops of concentrated hydrochloric acid andhydrogenated until hydrogen absorption has ceased. After filtering thereaction mixture off from the catalyst, 690 mg of colorless crystals isobtained (93% of theory).

Melting point: 245°-250° C. (decomposition).

Analysis

Calcd: C 52.58; H 5.21; N 16.72; O 25.47.

Found: C 52.83; H 5.19 N 16.84.

(c) 3-Aza-2-(4-hydroxybenzyl)pentane-1,5-diamine•Trihydrochloride

One gram (4.0 mmol) of 3-aza-2-(4-hydroxy-benzyl)-4-oxoglutaric aciddiamide (Example b) is reacted according to the directions given forExample 9e. The resultant colorless crystallized product weighs 1.19 g(93.7% of theory).

Melting point: 238° C.

Analysis

Calcd: C 41.61; H 6.98; N 13.23; O 5.03; Cl 33.13.

Found: C 41.60; H 6.95; N 13.17; Cl 33.33.

(d)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydroxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

According to the method described in Example 1a, 5.19 g (16.3 mmol) of3-aza-2-(4-hydroxybenzyl)pentane-1,5-diamine•trihydrochloride (Examplec) is reacted to yield 7.75 g (61% of theory) of the title compound inthe form of a highly viscous, clear liquid.

Analysis

Calcd: C 63.13; H 8.91; N 5.38; O 22.56.

Found: C 63.00; H 8.92; N 5.29.

(e)3,6,9-Triaza-5-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicAcid Bis(tert-butyl)diester

5.0 g (6.4 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example d) is reacted according to thedirections for Example 3a with bromoacetic acid benzyl ester, yielding4.6 g (74.8% of theory) of a colorless, viscous oil.

Analysis

Calcd: C 64.70; H 8.36; N 4.52; O 22.40.

Found: C 64.46; H 8.30; N 4.49.

(f)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-(4-benzyloxycarbonylmethoxybenzyl)undecanedioicAcid

In accordance with the method disclosed in Example 3b, 3.6 g (5.7 mmol)of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-benzyloxycarbonylmethoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 17e) yields 3.9 g (82% of theory)of a white color material.

Melting point: 145° C. (decomposition).

Analysis

Calcd: C 55.63; H 5.75; N 6.48; O 32.11.

Found: C 55.67; H 5.54; N 6.65.

The gadolinium complex was prepared using the method described inExample 1e.

Analysis

Calcd: C 44.93; H 4.27; N 5.24; O 25.93; Gd 19.61.

Found: C 45.01; H 4.21; N 5.15; Gd 19.70.

Gd (AAS): 19.61%.

The following salts are obtained in analogy to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 42.60; H 3.81; N 4.96; O 24.59; Gd 18.59; Na 5.43.

Found: C 42.61; H 3.82; N 4.90; Gd 18.40; Na 5.45.

Meglumine salt of the Gadolinium Complex

Analysis

Calcd: C 44.32; H 5.74; N 5.87; O 30.86; Gd 13.18.

Found: C 44.31; H 5.59; N 5.74; Gd 13.12.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 46.85; H 5.17; N 7.18; O 24.63; Gd 16.14.

Found: C 46.72; H 5.21; N 7.18; Gd 16.16.

EXAMPLE 18 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-benzyloxycarbonylaminopropoxy)benzyl!undecanedioic AcidBis(tert-butyl)diester

9.6 g (5.90 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 17d) yields, by following thedirections given for Example 1b, 4.2 g of a colorless oil (yield 74% oftheory).

Analysis

Calcd: C 64.30; H 8.51; N 5.76; O 21.41.

Found: C 64.45; H 8.55; N 5.76.

(b) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-aminopropoxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

In accordance with the method described in Example 1c, 2.8 g (1.25 mmol)of 3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-benzyloxycarbonylaminopropoxy)benzyl!undecanedioic acidbis(tert-butyl)diester (Example a) is hydrogenated, thus obtaining acolorless, viscous oil.

Yield: 2.28 g (95% of theory).

Analysis

Calcd: C 63.13; H 9.15; N 6.69; O 21.02.

Found: C 63.22; H 9.14; N 6.66.

(c) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-(maleimido)propoxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

According to the method described in Example 1d, starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-aminopropoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example b), the maleimide is obtained in a 90% yield (colorless,viscous oil).

Analysis

Calcd: C 62.86; H 8.35; N 6.10; O 22.62.

Found: C 62.75; H 8.41; N 6.01.

(d) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-4-(3-(maleimido)propoxy)benzyl!undecanedioic Acid

As described in Example 1e, starting with3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-(maleimido)propoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example c), the free penta acid is obtained in a 96% yield as a whitepowder.

Melting point: 285° C. (decomposition).

Analysis

Calcd: C 52.82; H 5.69; N 8.80; O 32.67.

Found: C 52.70; H 5.82; N 8.74.

Gadolinium Complex

As already described in Example 1e, the gadolinium complex is obtainedin quantitative yield.

Analysis

Calcd: C 42.52; H 4.20; N 7.08; O 26.30; Gd 19.88.

Found: C 42.39; H 4.21; N 7.19; Gd 19.55.

Gd (AAS): 18.63%.

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 40.28; H 3.74; N 6.71; O 24.91; Gd 18.23; Na 5.50.

Found: C 40.18; H 3.87; N 6.69; Gd 18.68; Na 5.57.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.70; H 5.85; N 7.28; O 30.52; Gd 13.63.

Found: C 42.60; H 5.70; N 7.36; Gd 13.61.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.89; H 5.12; N 8.72; O 24.91; Gd 16.32.

Found: C 44.90; H 5.11; N 8.63; Gd 15.98.

The following are obtained analogously to the directions for preparingthe gadolinium complex:

Indium Complex

Calcd: C 44.93; H 4.44; N 7.49; O 27.79; In 15.34.

Found: C 44.99; H 4.50; N 7.38; In 15.41.

Yttrium Complex

Calcd: C 45.48; H 4.59; N 7.75; O 28.75; Y 12.43.

Found: C 46.46; H 4.48; N 7.58; Y 12.15.

Ytterbium Complex

Calcd: C 41.68; H 4.12; N 6.95; O 25.79; Yb 21.45.

Found: C 41.75; H 4.08; N 6.92; Yb 21.32.

Samarium Complex

Calcd: C 42.89; H 4.24; N 7.15; O 26.53; Sm 19.18.

Found: C 42.88; H 4.36; N 7.22; Sm 19.15.

Praseodymium Complex

Calcd: C 43.42; H 4.29; N 7.24; O 26.86; Pr 18.19.

Found: C 43.43; H 4.24; N 7.30; Pr 18.32.

Cobalt Complex

Calcd: C 48.56; H 4.80; N 8.09; O 30.04; Co 8.51.

Found: C 48.55; H 4.49; N 8.12; Co 8.55.

EXAMPLE 19 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydrazinocarbonylmethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

With the directions given in Example 4a, 15.2 g (13.57 mmol) of3,6,9-triaza-5-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 17e) yields 9.6 g (83% of theory)of an oil that is highly viscous at room temperature.

Analysis

Calcd: C 60.61; H 8.63; N 8.21; O 22.53.

Found: C 60.49; H 8.52; N 8.23.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-(4-hydrazinocarbonylmethoxybenzyl)undecanedioicAcid

According to the method disclosed in Example 4b, 2.1 g (7.9 mmol) of3,6,9-triaza-3,6,9-tris-(tert-butoxycarbonylmethyl)-5-(4-hydrazinocarbonylmethoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) is reacted with trifluoroaceticacid. After the reaction mixture has been worked up, 3.1 g of whitecrystals (67% of theory) is obtained.

Melting point: 180° C. (decomposition).

Analysis

Calcd: C 48.33; H 5.81 B 12.25; O 33.59.

Found: C 48.15; H 5.83; N 12.31.

The gadolinium complex was prepared using the procedure described inExample 1e.

Analysis

Calcd: C 33.06; H 4.16; N 9.64; O 26.45; Gd 21.66.

Found: C 32.97; H 4.17; N 9.70; Gd 21.65.

Gd (AAS): 21.63%.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 35.88; H 3.66; N 9.09; O 24.94; Gd 20.42; Na 5.97.

Found: C 35.76; H 3.68; N 9.11; Gd 20.19; Na 6.00.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 39.85; H 5.69; N 8.79; O 31.56; Gd 14.10.

Found: C 39.80; H 5.72; N 8.71; Gd 14.02.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.46; H 5.16; N 10.91; O 24.94; Gd 17.51.

Found: C 41.51; H 5.15; N 10.78; Gd 17.36.

EXAMPLE 20 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

According to the directions given for Example 3a, 3.8 g (4.87 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 17d) yields 3.69 g (77% of theory)of a colorless oil.

Analysis

Calcd: C 65.89; H 8.70; N 4.26; O 21.13.

Found: C 65.66; H 8.63; N 4.38.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicAcid

According to the method set forth in Example 3b, 8.3 g (8.43 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) yields 5.51 g (93% of theory) ofa white crystallized product.

Melting point: 183° C. (decomposition).

Analysis

Calcd: C 58.02; H 6.44; N 5.97; O 29.55.

Found: C 58.09; H 6.31; N 6.03.

Gadolinium Complex

According to the method disclosed in Example 1e, the gadolinium complexis obtained in an almost quantitative yield.

Analysis

Calcd: C 47.59; H 4.93; N 4.89; O 24.24; Gd 18.32.

Found: C 47.70; H 4.70; N 4.82; Gd 18.50.

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 45.27; H 4.47; N 4.65; O 23.06; Gd 17.43; Na 5.09.

Found: C 45.30; H 4.48; N 4.62; Gd 17.28; Na 5.01.

Meglumine salt of the Gadolinium Complex

Analysis

Calcd: C 6.18; H 6.13; N 5.60; O 29.47; Gd 12.59.

Found: C 46.19; H 6.09; N 5.71; Gd 12.52.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 48.96; H 5.67; N 6.79; O 23.29; Gd 15.26.

Found: C 49.03; H 5.66; N 6.80; Gd 15.11.

EXAMPLE 21 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

According to the directions given for Example 4a, 13.05 g (13.26 mmol)of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-benzyloxycarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 20a) yields 10.72 g (89% of theory)of a colorless oil.

Analysis

Calcd: C 62.25; H 8.99; N 7.71; O 21.14.

Found: C 62.16; N 9.01; N 7.75.

(b)3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicAcid

According to the directions given for Example 4b, 4.5 g (4.95 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) yields 2.80 g (90% of theory) ofa white crystallized product.

Melting point: 217° C. (decomposition).

Analysis

Calcd: C 51.66; H 6.58; N 11.15; O 30.58.

Found: C 51.49; H 6.55; N 11.12.

Gadolinium Complex

In accordance with the method disclosed in Example 1e, the gadoliniumcomplex is obtained in an almost quantitative yield.

Analysis

Calcd: C 41.47; H 4.89; N 8.95; O 24.55; Gd 20.11.

Found: C 41.50; H 4.85; N 8.80; Gd 20.01.

The following salts are obtained in analogy to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.26; H 4.39; N 8.48; O 23.24; Gd 19.04; Na 5.56.

Found: C 39.18; H 4.33; N 8.40; Gd 19.00; Na 5.53.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.00; H 6.19; N 8.36; O 30.02; Gd 13.41.

Found: C 42.10; H 6.15; N 8.33; Gd 13.20.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.06; H 5.70; N 10.27; O 23.47; Gd 16.48.

Found: C 43.95; H 5.71; N 10.23; Gd 16.42.

EXAMPLE 22 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!undecanedioicAcid Bis(tert-butyl)diester

According to the directions given for Example 7a, 9.0 g (9.9 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicacid bis° (tert-butyl)diester (Example 21a) yields 6.58 g (68% oftheory) of a colorless oil.

Analysis

Calcd: C 62.74; H 8.77; N 7.17; O 21.3.

Found: C 62.63; H 8.72; N 7.21.

(b) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-4-(methacryloyl)hydrazinocarbonylpentamethylenoxybenzyl!undecanedioicAcid

According to the method set forth in Example 3b, 2.25 g (2.3 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(methacryloyl)-hydrazinocarbonylpentamethylenoxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example a) yields 1.41 g (88% of theory) ofa white crystallized product.

Melting point: 139° C. (decomposition).

Analysis

Calcd: C 53.51; H 6.51; N 10.06; O 29.89.

Found: C 53.52; H 6.50; N 10.13.

Gadolinium Complex

According to the method described in Example 1e, the gadolinium complexis obtained in an almost quantitative yield.

Analysis

Calcd: C 43.80; H 4.98; N 8.23; O 24.47; Gd 18.50.

Found: C 43.71; H 4.86; N 8.31; Gd 18.38.

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 41.60; H 4.61; N 7.82; O 23.24; Gd 17.57; Na 5.13.

Found: C 41.61; H 4.58; N 7.80; Gd 17.39; Na 5.08.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.53; H 6.25; N 7.89; O 29.64; Gd 12.66.

Found: C 43.53; H 6.20; N 7.88; Gd 12.45.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.78; H 5.81; N 9.58; O 23.45; Gd 15.36.

Found: C 45.79; H 5.77; N 9.55; Gd 15.20.

EXAMPLE 23 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic AcidBis(tert-butyl)diester

According to the method described in Example 2a, starting with3,6,9-triaza-3,6,9-tris-(tert-butoxycarbonylmethyl)-5-4-(3-aminopropoxy)benzyl!undecanedioic acid bis(tert-butyl)diester(Example 18b), the title compound is obtained in an 86% yield as an oil.

Analysis

Calcd: C 63.69; H 8.90; N 6.18; O 21.21.

Found: C 63.80; H 8.74; N 6.25.

(b) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-5-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic Acid

Starting with 3,6,9-triaza-tris(tert-butoxycarbonylmethyl)-5-4-(3-(methacrylamido)propoxy)benzyl!undecanedioic acidbis(tert-butyl)diester (Example a), the title compound is obtained in a91% yield in analogy to the procedure disclosed in Example 2b.

Analysis

Calcd: C 53.83; H 6.45; N 8.96; O 30.73.

Found: C 53.78; H 6.31; N 8.95.

Gadolinium Complex

Analogously to the directions in Example 1e, the gadolinium complex isobtained in a 98% yield.

Analysis

Calcd: C 43.17; H 4.78; N 7.19; O 24.65; Gd 20.18.

Found: C 43.33; H 4.60; N 7.15; Gd 20.12.

Gd (AAS); 20.23%

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 40.87; H 4.28; N 6.80; O 23.33; Gd 19.11; Na 5.58.

Found: C 40.88; H 4.25; N 6.78; Gd 19.05; Na 5.59.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.10; H 6.20; N 7.18; O 30.07; Gd 13.43.

Found: C 43.01; H 6.15; N 7.14; Gd 13.40.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.41; H 5.71; N 8.82; O 23.52; Gd 16.51.

Found: C 45.38; H 5.77; N 8.80; Gd 16.41.

EXAMPLE 24 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-carboxymethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

In accordance with the directions set forth in Example 8a, 4.9 g (5.16mmol) of3,6,9-triaza-5-(4-benzyloxycarbonylmethoxybenzyl)-3,6,9-tris(tert-butoxycaronylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 17e) yields 4.1 g of a colorless,viscous oil (93.2% of theory).

Analysis

Calcd: C 61.62; H 8.53; N 5.01; O 24.81.

Found: C 61.66; H 8.45; N 5.15.

(b) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5- 4-(2,3,4,5,6-pentahydroxyhexyl)-methylamino!carbonylmethoxybenzyl!undecanedioicAcid Bis(tert-butyl)diester

3.90 g (4.6 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-carboxymethoxybenzyl)undecanedioicacid bis(tert-butyl)diester is dissolved in 80 ml of tetrahydrofuran andcombined with 0.43 g (6.8 mmol) of triethylamine. At -5° C., 0.62 g(4.70 mmol) of chloroformic acid isobutyl ester in 30 ml oftetrahydrofuran is gently added, and the mixture is finally combinedwith 10 ml of an aqueous solution of 920 mg (4.7 mmol) ofN-methyl-D-glucamine. After 30 minutes of agitation at 0° C., thecooling bath is removed and the mixture allowed to warm up to roomtemperature. After evaporation of the solvent, the residue is purifiedby chromatography on silica gel, thus obtaining 3.73 g of a whitecrystalline compound (80% of theory), decomposing with browndiscoloration starting at 50° C.

Analysis

Calcd: C 59.15; H 8.53; N 5.51; O 26.79.

Found: C 59.18; H 8.60; N 5.55.

(c) 3,6,9-Triaza-3,6,9-tris (carboxymethyl)-5- 4-(2,3,4,5,6-pentahydroxyhexyl)methylamino!carbonylmethoxybenzyl!undecanedioicAcid

As described in Example 1e, 1.77 g (1.7 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5- 4-(2,3,4,5,6-pentahydroxyhexyl)methylamino!carbonylmethoxybenzyl!undecanedioicacid bis(tert-butyl)diester yields 1.04 g (83% of theory) of the titlecompound, melting point 132° C. (decomposition).

Analysis

Calcd: C 49.04; H 6.31; N 7.62; O 37.01.

Found: C 49.12; H 6.35; N 7.50.

Gadolinium Complex

Analogously to the directions in Example 1e, the gadolinium complex isobtained in a 98% yield.

Analysis

Calcd: C 40.53; H 4.87; N 6.30; O 30.59; Gd 17.68.

Found: C 40.61; H 4.71; N 6.35; Gd 17.92.

Gd (AAS): 17.86% by weight.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 38.62; H 4.42; N 6.00; O 29.15; Gd 16.85; Na 4.92.

Found: C 38.57; H 4.43; N 6.03; Gd 16.54; Na 4.88.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.30; H 6.06; N 6.56; O 33.76; Gd 12.29.

Found: C 41.17; H 5.98; N 6.59; Gd 11.97.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 43.01; H 5.60; N 7.91; O 28.64; Gd 14.81.

Found: C 42.96; H 5.52; N 7.97; Gd 14.85.

EXAMPLE 25 (a) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(2-propynyloxy)benzyl!suberic Acid Bis(tert-butyl)diester

In succession, a solution of 3.77 g (6.05 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl) subericacid bis(tert-butyl)diester (Example 1a) in 20 ml of toluene and asolution of 750 mg (6.3 mmol) of 3-bromopropyne in 20 ml of toluene areadded dropwise to a suspension of 390 mg of sodium hydride (80% inparaffin)(13.3 mmol) in 50 ml of toluene. After 2 hours, the mixture isfiltered, washed with water, and chromatographed on silica gel afterevaporation, thus obtaining 3.02 g of an oil (75.5% of theory).

Analysis

Calcd: C 65.43; H 8.54; N 4.23; O 21.78.

Found: C 65.33; H 8.60; N 4.30.

(b) 3,6-Diaza-3,6-bis(carboxymethyl)-4- 4-(2-propynyloxy)benzyl!subericAcid

According to the directions given for Example 1e, 1.35 g (2 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(2-propynyloxy)benzyl!suberic acid bis(tert-butyl)diester is reacted,thus obtaining a white powder (740 mg, 83% of theory) melting at 140° C.with decomposition.

Analysis

Calcd: C 55.04; H 5.54; N 6.41; O 32.99.

Found: C 55.13; H 5.59; N 6.40.

Gadolinium Complex

The gadolinium complex is obtained as described in 1e.

Analysis

Calcd: C 40.67; H 3.58; N 4.74; O 24.37; Gd 26.62.

Found: C 40.80; H 3.60; N 4.70; Gd 26.36.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.21; H 3.29; N 4.57; O 23.50; Gd 25.66; Na 3.75.

Found: C 39.22; H 3.22; N 4.60; Gd 25.36; Na 3.74.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 41.26; H 4.87; N 5.34; O 28.50; Gd 20.00.

Found: C 41.22; H 4.89; N 5.32; Gd 20.31.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.59; H 4.31; N 6.20; O 23.64; Gd 23.23.

Found: C 42.48; H 4.30; N 6.15; Gd 23.15.

EXAMPLE 26 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(2-propynyloxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

5.36 g (6.87 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) is dissolved in 70 ml oftoluene and gently combined with 363 mg of sodium hydride (15.1 mmol).To this mixture is added dropwise 858 mg of 3-bromopropyne (7.2 mmol) in30 ml of toluene.

After 2 hours, the solution is filtered, the organic phase is washedtwice with water, and the solvent is removed. After chromatography onsilica gel, 4.89 g of a colorless oil is obtained (87% of theory).

Analysis

Calcd: C 64.60; H 8.74; N 5.13; O 21.51.

Found: C 64.57; H 8.64; N 5.15.

(b) 3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4-4-(2-propynyloxy)benzyl!undecanedioic Acid

In accordance with the directions given for Example 1e, 4.35 g (5.32mmol) of 3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-4-(2-propynyloxy)benzyl!undecanedioic acid bis(tert-butyl)diester isreacted, thus obtaining a white powder (2.42 mg, 85% of theory) meltingat 142° C. with decomposition.

Analysis

Calcd: C 53.62; H 5.81; N 7.81; O 32.74.

Found: C 53.66; H 5.85; N 7.82.

Gadolinium Complex

The gadolinium complex is obtained as described in 1e.

Analysis

Calcd: C 41.67; H 4.07; N 6.07; O 25.44; Gd 22.73.

Found: C 41.42; H 4.12; N 6.27; Gd 22.59.

In analogy with the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.18; H 3.56; N 5.71; O 23.92; Gd 21.37; Na 6.24.

Found: C 38.97; H 3.55; N 5.65; O 23.90; Gd 21.53; Na 6.25.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.17; H 5.77; N 6.47; O 31.04; Gd 14.53.

Found: C 42.01; H 5.63; N 6.50; O 30.98; Gd 14.55.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.48; H 5.13; N 8.10; O 24.07; Gd 18.20.

Found: C 44.51; H 5.08; N 8.12; O 24.10; Gd 18.07.

EXAMPLE 27 (a) 3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(2-propynyloxy)benzyl!undecanedioic Acid Bis(tert-butyl)diester

4.57 g (5.8 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 17d) is reacted, as described forExample 26a, with 310 mg of sodium hydride and 730 mg of 3-bromopropyneto yield the title compound. The title compound is obtained as acolorless oil with a yield of 4.07 g (74% of theory).

Analysis

Calcd: C 64.60; H 8.74; N 5.13; O 21.51

Found: C 64.64; H 8.70; N 5.20

(b) 3,6,9-Triaza-3,6,9-tris (carboxymethyl)-5- 4-(2-propynyloxy)benzyl!undecanedioic Acid

4.69 g (5.7 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-4-(2-propynyloxy)benzyl!undecanedioic acid bis(tert-butyl)diester isreacted in accordance with the direction given for Example 1e, thusobtaining a white powder melting at 135° C. with decomposition.

Analysis

Calcd: C 53.62; H 5.81; N 7.81; O 32.74

Found: C 53.66; H 5.90; N 7.75

Gadolinium Complex

The gadolinium complex is obtained as disclosed in 1e.

Analysis

Calcd: C 41.67; H 4.07; N 6.07; O 25.44; Gd 22.73.

Found: C 41.66; H 4.11; N 6.04; Gd 22.51.

The following salts are obtained in analogy to the method described in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 39.18; H 3.56; N 5.71; O 23.92; Gd 21.37; Na 6.24.

Found: C 39.32; H 3.55; N 5.80; O 23.81; Gd 21.50; Na 6.27.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.17; H 5.77; N 6.47; O 31.04; Gd 14.53.

Found: C 42.15; H 5.60; N 6.51; O 31.05; Gd 14.37.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.48; H 5.13; N 8.10; O 24.07; Gd 18.20.

Found: C 44.45; H 5.15; N 8.11; O 24.17; Gd 18.19.

EXAMPLE 28 (a) 11- 4-N,N,N',N'-Tetrakis(tert-butoxycarbonylmethyl)-2,3-diaminopropyl!phenoxyacetyl!aminoundecanoicAcid 2-(tert-Butoxycarbonyl)hydrazide!

Under continuous cooling to below 5° C., 30 ml of a solution of 3.65 g(26.8 mmol) of chloroformic acid isobutyl ester in tetrahydrofuran isadded dropwise to a solution of 18.23 g (26.78 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)subericacid bis(tert-butyl)diester (Example 8a) and 2.7 g (26.8 mmol) oftriethylamine in 200 ml of dry tetrahydrofuran. Half an hour aftercompletion of this addition, during which time cooling and agitation arecontinued, a solution of 8.44 g (26.8 mmol) of 11-aminoundecanoic acid2-(tert-butoxycarbonyl)hydrazide is added gradually thereto. Then themixture is allowed to warm up to room temperature under agitation andthe solvent is evaporated. The residue is taken up in 400 ml of toluene,and water-soluble proportions are extracted with saturated sodiumchloride solution. After washing with water and drying, the solvent isevaporated and the oil is subjected to purification by chromatography onsilica gel, yielding 20.1 g (79% of theory) of a colorless oil.

Analysis

Calcd: C 63.19; H 9.22; N 7.36; O 20.2.

Found: C 63.17; H 9.25; N 7.31.

(b) 11- 4-N,N,N',N'-Tetrakis(carboxymethyl)-2,3-diaminopropyl!phenoxyacetyl!aminoundecanoicAcid Hydrazide

As described for Example 1e, the tert-butyl esters can be split off withtrifluoroacetic acid at room temperature. Under these conditions, incase of 11- 4-N,N,N',N'-tetrakis(tert-butoxycarbonylmethyl)-2,3-diaminopropyl!phenoxyacetyl!aminoundecanoicacid 2-(tert-butoxycarbonyl)hydrazide!, the tert-butoxycarbonyl blockinggroup of the acid hydrazide is likewise split off, thus obtaining, usingthe procedure described in Example 1e, from 12.56 g of starting material(13.2 mmol) in a 77.3% yield 6.68 g of a white crystalline compoundwhich begins to melt at 115° C. under decomposition.

Analysis

Calcd: C 55.11; H 7.24; N 10.71; O 26.92.

Found: C 54.98; H 7.30; N 10.77.

Gadolinium Complex

Analysis

Calcd: C 44.59; H 5.48; N 8.66; O 21.78; Gd 19.46.

Found: C 44.55; H 5.49; N 8.71; Gd 19.21.

Analogously to the directions given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 43.41; H 5.22; N 8.43; O 21.20; Gd 18.94; Na 2.77.

Found: C 43.36; H 5.19; N 8.47; Gd 18.59; Na 2.76.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.30; H 6.12; N 8.57; O 25.51; Gd 15.67.

Found: C 44.33; H 6.15; N 8.51; Gd 15.76.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 45.67; H 5.86; N 9.39; O 21.47; Gd 17.58.

Found: C 45.77; H 5.80; N 9.28; Gd 17.38.

EXAMPLE 29 (a) 11- 4- 4-(tert-Butoxycarbonylmethyl)!-4-aza-2,6-dibis(tert-butoxycarbonylmethyl)amino!hexyl!-phenoxyacetyl!aminoundecanoicAcid

2-(tert-Butoxycarbonyl)hydrazide!

8.4 g (10 mmol) of3,6,9-triaza-3,6,9-tris-(tert-butoxycarbonylmethyl)-4-(4-carboxymethoxybenzyl)-undecanoicacid bis(tert-butyl)diester (Example 16a) is reacted according to thedirections for Example 28a with the equivalent amounts of triethylamine,chloroformic acid isobutyl ester and 11-aminoundecanoic acid2-(tert-butoxycarbonyl)hydrazide. After purification by columnchromatography, 8.74 g (77% of theory) of a colorless oil is produced.

Analysis

Calcd: C 62.40; H 9.05; N 7.40; O 21.13.

Found: C 62.31; H 9.10; N 7.36.

(b) 11- 4- 4-(Carboxymethyl)-4-aza-2,6-dibis(carboxymethyl)amino!hexyl!phenoxyacetyl!aminoundecanoic AcidHydrazide

As described for Examples1e and 28b, 6.32 g (5.6 mmol) of 11- 4-4-(tert-butoxycarbonylmethyl)-4-aza-2,6-dibis(tert-butoxycarbonylmethyl)amino!hexyl!-phenoxyacetyl!aminoundecanoicacid 2-(tert-butoxycarbonyl)hydrazide!yields, in a 76% yield, the titlecompound in the form of colorless crystals.

Melting point: 185° C. (decomposition).

Analysis

Calcd: C 54.10; H 7.21; N 11.13; O 27.55.

Found: C 53.98; H 7.23; N 11.10.

Gadolinium Complex

Analysis

Calcd: C 44.92; H 5.65; N 9.24; O 22.87; Gd 17.29.

Found: C 44.95; H 5.60; N 9.26; Gd 17.33.

The following salts are obtained analogously to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 42.85; H 5.18; N 8.81; O 21.82; Gd 16.50; Na 4.82.

Found: C 42.69; H 5.12; N 8.80; Gd 16.25; Na 4.83.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.36; H 6.59; N 8.62; O 28.31; Gd 12.10.

Found: C 44.35; H 6.50; N 8.63; Gd 12.15.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 46.65; H 6.24; N 10.36; O 22.19; Gd 15.54.

Found: C 46.66; H 6.30; N 10.24; Gd 15.32.

EXAMPLE 30 (a) 11- 4- 3- (tert-Butoxycarbonylmethyl)-3-aza!-2-bis(tert-butoxycarbonylmethyl)amino!methyl!-5-bis(tert-butoxycarbonylmethyl)amino!pentyl!-5phenoxyacetyl!aminoundecanoic Acid 2-(tert-Butoxycarbonyl)hydrazide!

According to the directions for Example 28a, 6.13 g (7.3 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-carboxymethoxybenzyl)undecanoicacid bis(tert-butyl)diester (Example 24a) is reacted with equivalentamounts of triethylamine, chloroformic acid isobutyl ester, and11-aminoundecanoic acid 2-(tert-butoxycarbonyl)hydrazide. Afterpurification by column chromatography, 7.04 g (85% of theory) of acolorless oil is produced.

Analysis

Calcd: C 62.4; H 9.05; N 7.40; O 21.13.

Found: C 62.31; H 9.17; N 7.56.

(b) 11- 4- 3- (Carboxymethyl)-3-aza!-2-bis(carboxymethyl)amino!methyl!-5-bis(carboxymethyl)amino!-pentyl!phenoxyacetyl!aminoundecanoic AcidHydrazide

In accordance with the procedure described for Examples1e and 28b, 5.38g (4.7 mmol) of 11- 4- 3- (tert-butoxycarbonylmethyl)-3-aza!-2-bis(tert-butoxycarbonylmethyl)amino!methyl!-5-bis(tert-butoxy-carbonylmethyl)amino!pentyl!phenoxyacetyl!aminoundecanoicacid 2-(tert-butoxycarbonyl)hydrazide! yields 2.93 g (82% of theory) ofcolorless crystals.

Melting point: 192° (decomposition).

Analysis

Calcd: C 54.1; H 7.21; N 11.13; O 27.55.

Found: C 54.09; H 7.28; N 11.11.

Gadolinium Complex

Analysis

Calcd: C 44.92; H 5.65; N 9.24; O 22.87; Gd 17.29.

Found: C 44.80; H 5.66; N 9.22; Gd 17.03.

Analogously to the directions indicated in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 42.85; H 5.18; N 8.81; O 21.82; Gd 16.50; Na 4.82.

Found: C 42.88; H 5.12; N 8.83; Gd 16.91; Na 4.88.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.36; H 6.59; N 8.62; O 28.31; Gd 12.10.

Found: C 44.32; H 6.30; N 8.71; Gd 12.12.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: 46.65; H 6.24; N 10.36; O 22.19; Gd 15.54.

Found: C 46.39; H 6.26; N 10.32; Gd 15.61.

EXAMPLE 31 (a)3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-oxiranylmethoxy)benzylsubericAcid Bis(tert-butyl)diester

17.38 g (27.9 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)subericacid bis(tert-butyl)diester (Example 1a) is dissolved with 900 mg (3mmol) of 80% sodium hydride in paraffin under agitation in 300 ml oftoluene and, at 40° C., combined dropwise with a solution of 2.6 g (28mmol) of epichlorohydrin. After one hour, the mixture is gently combinedwith 100 ml of water. After shaking, the phases are separated and thenthe organic phase is concentrated after drying. Chromatographicpurification yields 15.5 g (22.8 mmol, 82% of theory) of a colorlessoil.

Analysis

Calcd: C 63.69; H 8.61; N 4.12; O 23.56.

Found: C 63.57; H 8.62; N 4.07.

(b) 15- 4-N,N,N',N'-Tetrakis(tert-butoxycarbonylmethyl)-2,3-diaminopropyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid 2-(Butoxycarbonyl)hydrazide

7.35 g (10.8 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-(4-oxiranylmethoxy)benzylsubericacid bis(tert-butyl)diester, dissolved in 100 ml of diethyl ether, iscombined with 3.41 g (10.8 mmol) of 11-aminoundecanoic acid2-(tert-butoxycarbonyl)hydrazide in 100 ml of tetrahydrofuran, andheated to reflux for 2 hours. After evaporation of the solvent, thecompound is obtained analytically pure as a colorless oil.

Yield: 9.54 g (88.5% of theory).

Analysis

Calcd: C 62.81; H 9.22; N 7.04; O 20.91.

Found: C 62.65; H 9.23; N 7.15.

(c) 15- 4-N,N,N',N'-Tetrakis(carboxymethyl)-2,3-diaminopropyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid Hydrazide

4.36 g (4.3 mmol) of 15- 4-2,3-N,N,N',N'-tetrakis(tert-butoxycarbonylmethyl)-2,3-diaminopropyl!phenoxy!-12-aza-14-hydroxypentadecanoicacid 2-(butoxycarbonyl)hydrazide! is dissolved at room temperature in 50ml of trifluoroacetic acid and worked up after 5 hours as described forExample 1e, yielding 2.86 g (3.2 mmol; 73% of theory) of colorlesscrystals.

Melting point: 145° C. (decomposition).

Analysis

Calcd: C 55.59; H 7.62; N 10.45; O 26.27.

Found: C 55.60; H 7.49; N 10.55.

Gadolinium Complex

Calcd: C 45.18; H 5.87; N 8.49; O 21.35; Gd 19.08.

Found: C 45.20; H 5.88; N 8.62; Gd 19.09.

Analogously to the direction given in 1e, the following salts areobtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 44.01; H 5.59; N 8.27; O 20.80; Gd 18.58; Na 2.71.

Found: C 43.95; H 5.61; N 8.23; Gd 18.38; Na 2.77.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.82; H 6.33; N 8.25; O 28.14; Gd 15.44.

Found: C 44.69; H 6.43; N 8.20; Gd 15.40.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 46.24; H 6.09; N 9.24; O 21.11; Gd 17.29.

Found: C 46.23; H 6.11; N 9.28; Gd 17.17.

EXAMPLE 32 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-oxiranylmethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

16.35 g (21.0 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-hydroxybenzyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) is dissolved with 630 mg (21mmol) of sodium hydride (80% in paraffin) under agitation in 300 ml oftoluene and, at 40° C., combined dropwise with a solution of 1.95 g (21mmol) of epichlorohydrin in 20 ml of toluene. After the reaction mixturehas been worked up as disclosed for Example 31a, 15.4 g (88% of theory)of a colorless oil is obtained.

Analysis

Calcd: C 63.20; H 8.80; N 5.02; O 22.96.

Found: C 63.35; H 8.76; N 5.09.

(b) 15- 4-4-Aza-2,6-diamino-N,N,N',N",N"-pentakis(tert-butoxycarbonylmethyl)hexyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid (2-tert-Butoxycarbonyl)hydrazide.

7.5 g (9.0 mmol) of3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-4-(4-oxiranylmethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester, dissolved in 100 ml of dry diethyl ether iscombined with 2.85 g (9.0 mmol) of 11-aminoundecanoic acid(2-tert-butoxycarbonyl)hydrazide in 50 ml of dry tetrahydrofuran andheated under reflux for 2 hours. After evaporation of the solvent andchromatography on silica gel, 9.12 g (88% of theory) of a colorless oilis obtained.

Analysis

Calcd: C 62.58; H 9.27; N 7.29; O 20.84.

Found: C 62.83; H 9.30; N 7.28.

(c) 15- 4-4-Aza-2,6-diamino-N,N,N',N",N"-pentakis(carboxymethyl)hexyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid Hydrazide

As described for Example 1e, the title compound is obtained in an 80%yield in the form of white crystals having a melting point above 135° C.(decomposition).

Analysis

Calcd: C 54.53; H 7.58; N 10.90; O 26.88.

Found: C 54.62; H 7.48; N 10.88.

Gadolinium Complex

Calcd: C 45.44; H 5.99; N 9.08; O 22.48; Cd 16.99.

Found: C 45.38; H 6.02; N 9.05; Cd 16.76.

The following salts are obtained in analogy to the directions given in1e:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 43.38; H 5.51; N 8.67; O 21.46; Gd 16.22; Na 4.74.

Found: C 43.42; H 5.49; N 8.70; Gd 16.03; Na 4.77.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.80; H 6.67; N 8.53; O 28.01; Gd 11.97.

Found: C 44.84; H 6.70; N 8.51; Gd 11.88.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 47.15; H 6.34; N 10.23; O 21.91; Gd 14.35.

Found: C 47.14; H 6.20; N 10.25; Gd 14.50.

EXAMPLE 33 (a)3,6,9-Triaza-3,6,9-tris(tert-butoxycarbonylmethyl)-5-(4-oxiranylmethoxybenzyl)undecanedioicAcid Bis(tert-butyl)diester

Analogously to Example 32a, the title compound is produced from thecompound disclosed in Example 17d in an 82% yield as a colorless oil.

Analysis

Calcd: C 63.20; H 8.80; N 5.02; O 22.96.

Found: C 63.15; H 8.69; N 4.93.

(b) 15- 4- 3-Aza-3-(tert-butoxycarbonylmethyl)-2-bis(tert-butoxycarbonylmethyl)amino!methyl!-5-bis(tert-butoxycarbonylmethyl)amino!pentyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid 2-(tert-Butoxycarbonyl)hydrazide!

As described for Example 32b, the title compound is obtained in an 81%yield as a clear oil from the compound described in 33a.

Analysis

Calcd: C 62.58; H 9.27; N 7.29; O 20.84.

Found: C 62.47; H 9.30; N 7.30.

(c) 15- 4- 3-Aza-3-(carboxymethyl)-2- bis(carboxymethyl)amino!methyl!-5-bis(carboxymethyl)amino!-pentyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid Hydrazide

As described for Example 32c, the title compound is obtained from thecompound described in 32b as a colorless oil in an 83% yield.

Analysis

Calcd: C 54.53; H 7.58; N 10.90; O 26.88.

Found: C 54.60; H 7.55; N 10.95.

Gadolinium Complex

Calcd: C 45.44; H 5.99; N 9.08; O 22.48; Gd 16.99.

Found: C 45.43; H 5.70; N 9.21; Gd 17.01.

Analogously to the procedure of 1e, the following salts are obtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 43.38; H 5.51; N 8.67; O 21.46; Gd 16.22; Na 4.74.

Found: C 43.45; H 5.30; N 8.76; Gd 15.90; Na 4.73.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 44.80; H 6.67; N 8.53; O 28.01; Gd 11.97.

Found: C 44.95; H 6.66; N 8.50; Gd 11.51.

Morpholine Salt of the Gadolinium Complex

Analysis

Calcd: C 47.15; H 6.34; N 10.23; O 21.91; Gd 14.35.

Found: C 47.16; H 6.32; N 10.31; Gd 14.39.

EXAMPLE 34 (a) 3,6-Diaza-2,7-dioxo-4-(4-hydroxybenzyl)suberic AcidDiethyl Ester

23 g (96.4 mmol) of 1,2-diamino-l-(4-hydroxybenzyl)ethanedihydrochloride is stirred with 21.4 g (212 mmol) of triethylamine in300 ml of dry tetrahydrofuran (THF) for one hour at 50° C. andthereafter, at 5°-10° C., combined dropwise with a cooled solution ofoxalic acid ethyl ester chloride (28.96, 212 mmol) with 21.4 g (212mmol) of triethylamine in 200 ml of THF. After this adding step, themixture is stirred for another hour at room temperature, heated for 15minutes to reflux, and the solvent evaporated. The mixture is made intoa slurry in 500 ml of toluene, thoroughly washed with water, and theorganic phase is concentrated again after drying. The product,analytically pure, remains in the form of colorless crystals in an 86%yield (33.9 g).

Melting point: 176° C. (decomposition).

Analysis

Calcd: C 55.73; H 6.05; N 7.64; O 30.56.

Found: C 55.61; H 6.15; N 7.63.

(b) 3,6-Diaza-2,7-dioxo-4-(4-hydroxybenzyl)suberic Acid Diamide

In accordance with the method described in Example 17B, 17.32 g (47.2mmol) of 3,6-diaza-2,7-dioxo-4-(4-hydroxybenzyl)suberic acid diethylester is reacted to the amide, thus obtaining in a 98% yield 14.28 g ofwhite crystals which melt starting with 285° C. under browndiscoloration.

Analysis

Calcd: C 50.64; H 5.23; N 18.17; O 25.94.

Found: C 50.66; H 5.20; N 18.23.

(c) 3,6-Diaza-l,8-diamino-4-(4-hydroxybenzyl)octane (Hydrochloride)

6.16 g (20 mmol) of 3,6-diaza-2,7-dioxo-4-(4-hydroxybenzyl)suberic aciddiamide is made into a slurry with 200 ml of absolute THF and a gradualstream of diborane (22.6 g of NaBH₄ and 205 ml of boron trifluorideetherate) is passed with the aid of nitrogen through the reactionmixture under agitation. The mixture is refluxed for 96 hours, half theoriginal quantity of diborane is once more introduced, and the mixtureis refluxed for another 2 days. Thereafter, the mixture is worked up asdescribed in connection with Example 9e. The yield is 5.65 g (71% oftheory) of colorless crystals decomposing starting with 90° C.

Analysis

Calcd: C 39.36; H 7.11; N 14.21; O 4.03; Cl 35.36.

Found: C 39.42; H 7.13; N 14.03; Cl 35.31.

(d)3,6,9,12-Tetraaza-3,6,9,12-tetrakis(tert-butoxycarbonylmethyl)-7-(4-hydroxybenzyl)tetradecanedicarboxylicAcid Bis(tert-butyl)diester

According to the directions given for Example 1a, 13.21 g (33.1 mmol) of3,6-diaza-1,8-diamino-4-(4-hydroxybenzyl)octane tetrahydrochloride isreacted with 38.7 g (198.6 mmol) of bromoacetic acid tert-butyl esterand 17.2 g (204.7 mmol) of NaHCO₃ in 500 ml of dimethylformamide toobtain 26.11 g (84% of theory) of a colorless oil.

Analysis

Calcd: C 62.79; H 9.03; N 5.97; O 22.19.

Found: C 62.78; H 8.87; N 5.96.

(e) 3.6.9.12-Tetraaza-3,6,9,12-tetrakis(tert-butoxycarbonylmethyl)-7-4-(3-amino)propoxybenzyl!tetradecanedicarboxylic AcidBis(tert-butyl)diester

The 4-hydroxybenzyl compound obtained according to (d) is alkylatedfollowing the directions given for 1b. The thus-obtained product (72%yield) is utilized without isolation in the subsequent reaction stage(splitting off the amine blocking group according to the procedure oflc), thus obtaining the title compound in an 82% yield, analyticallypure, as a colorless oil.

Analysis

Calcd: C 62.75; H 9.31; N 7.03; O 20.89.

Found: C 62.70; H 9.28; N 7.13.

(f) 3,6,9,12-Tetraaza-3,6,9,12-tetrakis(carboxymethyl)-7-4-(3-amino)propoxybenzyl!tetradecanedicarboxylic Acid

2.56 g (2.5 mmol) of the ester obtained according to (e) is stirred in30 ml of trifluoroacetic acid (anhydrous) for 2 hours at roomtemperature. The mixture is then poured into 300 ml of ether, suctionedoff, suspended furthermore twice with respectively 100 ml of ether, anddried; there remains 1.4 g of colorless crystals (85% of theory).

Melting point: above 135° C. (decomposition).

Analysis

Calcd: C 51.13; H 6.59; N 10.64; O 31.62.

Found: C 51.25; H 6.62; N 10.50.

The gadolinium complex is obtained as indicated in 1e:

Gadolinium Complex:

Calcd: C 41.42; H 4.96; N 8.62; O 25.61 Cd 19.36.

Found: C 41.53; H 5.01; N 8.39 Cd 19.09.

Analogously to the directions in 1e, the following,salts are obtained:

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 38.31; H 4.24; N 7.97; O 23.69; Gd 17.91; Na 7.85.

Found: C 38.25; H 4.11; N 7.56; Gd 18.05; Na 7.86.

Meglumine Salt of the Gadolinium Complex

Analysis

Calcd: C 42.11; H 6.56; N 8.01; O 32.05; Gd 11.25.

Found: C 42.25; H 6.70; N 8.09; Gd 11.13.

EXAMPLE 35 Indium Complex of the Conjugate of3,6,9-Triaza-3,6,9-tris(carboxymethyl)-4- 4-3-(maleimido)propoxy!benzyl!undecanedioic Acid with Fab Fragments ofMonoclonal Antibody 7B10D11

(a) Production of F(ab')₂ Fragments:

16 mg (100 nanomoles) of the antibody 7B10D11 is dissolved in 1 ml of amixture of 0.1-molar acetate buffer (pH 4.5) and 0.1-molar sodiumchloride solution and, after adding 0.3 mg of pepsin, is incubated for20 hours at 37° C. After purification over "Ultragel" AcA 44 (company:LKB) at pH 7.0 and after freeze-drying, 6.3 mg (63% of theory) of thedesired fragments is obtained.

(b) Production and Coupling of Fab Fragments:

15 mg (150 nmol) of the fragments obtained according to (a) is dissolvedin 14.5 ml of 0.1-molar phosphate buffer (pH 6.0) and dissolved with0.15 ml of a 0.1-molar mercaptoethylamine solution in 0.1-molarphosphate buffer (pH 6.0) with the addition of 15 mmol ofethylenediaminetetraacetic acid. After 2 hours of incubating at 37° C.,the mixture is separated under a protective argon blanket over a"Sephadex" G 25 column. Determination of the sulfhydryl groups yields238 nmol of SH-groups in the reaction batch.

0.7 mg (2.15 μmol) of the complexing agent described in Example 9j isdissolved in 10 ml of 0.1-molar phosphate buffer (pH 6.0). Theabove-prepared solution of the Fab fragment is added thereto at 4° C.and the mixture is allowed to react overnight with slight shaking (atmaximally 4° C.). Thereafter the mixture is eluted over a cationexchanger, dialyzed against 0.1-molar ammonium acetate solution, andlyophilized, thus obtaining 14.1 mg of a white powder.

1 ml of ¹¹¹ InCl₃ solution (pH 5.5, 83 mCi/ml) is added to a solution ofthe conjugate in 25 ml of buffer (20 mmol, sodium acetate; 150 mmol,sodium chloride) and incubated for 4 hours. Thereafter another 5 ml of0.1-molar sodium acetate solution is added, the mixture is dialyzed andlyophilized, and the product is 13.82 mg of a white powder having aspecific activity of 5 mCi/mg.

EXAMPLE 36 ¹¹¹ Indium Complex of the Conjugate of the MonoclonalAntibody 7B10D11 with 15- 4-4-Aza-2,6-diamino-N,N,N',N",N"-pentakis(carboxymethyl)hexyl!phenoxy!-12-aza-14-hydroxypentadecanoicAcid Hydrazide

30 nmol of the antibody is bound to a macroporous, strongly acidiccation exchanger previously equilibrated with a 0.1-molar sodium acetatebuffer (pH 5) and present in a column protected from incident light byan aluminum foil. Then the mixture is flushed with 0.03-molar sodiumperiodate in acetate buffer until the periodate appears in the eluate.Flushing is interrupted for 30 minutes, then the mixture is washed withacetate buffer and thereafter a solution is applied 0.03-molar withrespect to the above hydrazide (Example 32) and 0.1-molar with respectto sodium cyanoborohydride. After 2 hours, complexing agent that has notentered into the coupling reaction is eluted with acetate buffer; theconjugate is eluted with a sodium chloride gradient. After desalting,the mixture is freeze-dried, thus obtaining 4.5 mg of conjugate which isconverted into the 111indium complex as described in Example 35.

EXAMPLE 37 (a) N-Carbobenzoxyserin (2-carbobenzoxyaminoethylen) amide

7.34 g (30.7 mmol) of N-carbobenzoxyserine is reacted in accordance withthe directions given in Example 9b with the corresponding amounts ofchloroformic acid ethyl ester, triethylamine andN-(2-aminoethyl)carbamic acid benzyl ester hydrochloride, and worked up,thus obtaining 10.33 g (81%) of a colorless crystallized product.

Melting point: 167° C.

Analysis

Calcd: C 60.71; H 6.06; N 10.11; O 23.1.

Found: C 60.75; H 5.98; N 10.15.

(b)(2-Aminoethyl) serinamide

13.46 g of N-carbobenzoxyserin(2-carbobenzoxyaminoethylen)amide ishydrogeanted in 200 ml of methanol in the presence of 1.37 g of 10%palladium-carbon until hydrogen is no longer absorbed. The mixture isfiltered off from the catalyst and all volatile components are removedby an oil pump. A viscous, partially crystalline oil remains.

Yield: 4.67 g (98%)

Analysis

Calcd: C 40.80; H 8.89; N 28.55; O 21.74.

Found: C 40.71; H 8.85; N 28.30.

(c) 1-Hydroxymethyl-l,3,5-triazapentane Trihydrochloride

Analogously to the directions for Example 9e, the title compound isobtained in a 67% yield from the aforedescribed amide as a whitecrystalline powder.

Melting point: 236° C. (decomposition)

Analysis

Calcd: C 24.75; H 7.47; N 17.32; O 6.59; Cl 43.84.

Found: C 24.71; H 7.40; N 17.41; Cl 43.98.

(d)4-Hydroxymethyl-3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)undecanoicAcid Di-tert-butyl-diester

The title compound is obtained in a 78% yield as a colorless oilanalogously to the directions for Example 1a (after chromatography onsilica gel with ether/hexane=1/2).

Analysis

Calcd: C 59.71; H 9.31; N 5.97; O 25.0.

Found: C 59.66; H 9.32; N 5.99.

(e) The gadolinium complex and, respectively, its salts are obtained asdescribed in Example 1e.

Gadolinium Complex

Analysis

Calcd: C 42.55; H 5.95; N 9.92; O 41.56.

Found: C 43.08; H 5.88; N 9.73.

Sodium Salt of the Gadolinium Complex

Analysis

Calcd: C 30.04; H 3.53; N 7.00; O 29.35; Gd 26.22; Na 3.83.

Found: C 30.51; H 3.55; N 7.04; Gd 26.22; Na 3.88.

N-Methylglucamine Salt of the Gadolinium Complex

Analysis

Calcd: C 31.19; H 3.83; N 7.27; O 30.46; Gd 27.22.

Found: C 31.70; H 3.84; N 7.21; Gd 27.36.

EXAMPLE 38 (a) Bis-1,4- 4- 2,6-dibis(tert-butoxycarbonylmethyl)amino!-4-(tert-butoxycarbonylmethyl)azahexamethylene!phenoxy!butane

13.7 g (17.56 mmol) of4-(4-hydroxybenzyl)-3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) is dissolved in dry toluene(100 ml), gently combined with 530 mg (17.6 mmol) of NaH (80% suspensionin paraffin), and heated for 10 minutes to 40°-50° C. Thereafter themixture is cooled to 0° C. and combined with 1.9 g (8.8 mmol) ofdibromobutane in 10 ml of toluene. The mixture is allowed to warm up toroom temperature and then heated for another 30 minutes to 80°-100° C.After filtration over glass wool and evaporation of the solvent, themixture is chromatographed on silica gel, thus obtaining 10.5 g (6.5mmol, 74% of theory) of a colorless oil.

Analysis

Calcd: C 63.99; H 8.99; N 5.2; O 21.8.

Found: C 64.57; H 9.11; N 5.18.

(b) Bis-1,4- 4- 2,6-dibis(carboxymethyl)amino!-4-(carboxymethyl)azahexamethylene!phenoxy!butane

As described for Example 1e, the free complexing agent is obtained in a73% yield in the form of white crystals, melting point 228° C.(decomposition).

Analysis

Calcd: C 52.46; H 6.12; N 7.98; O 33.42.

Found: C 52.1; H 6.12; N 8.05.

The gadolinium complex, as well as its salts, are obtainedquantitatively as described in Example 1e.

Gd Complex

Analysis

Calcd: C 40.58; H 4.29; N 6.17; O 25.85; Gd 32.09.

Found: C 40.21; H 4.32; N 6.18; Gd 23.32.

Sodium Salt of the Gd Complex

Analysis

Calcd: C 39.31; H 4.01; N 5.97; O 25.04; Na 3.27; Gd 22.37.

Found: C 38.91; H 3.94; N 6.08; Na 3.31; Gd 22.11.

N-Methylglucamine Salt of the Gd Complex

Analysis

Calcd: C 41.48; H 5.92; N 6.53; O 31.36; Gd 14.68.

Found: C 42.27; H 5.84; N 6.47; Gd 14.62.

EXAMPLE 39 (a) N,N'-Bis 4-3-(tert-butoxycarbonylmethyl)aza-5-bis(tert-butoxycarbonylmethyl)amino-2-bis(tert-butoxycarbonylmethyl)aminomethyl!pentamethylenephenoxyacetyl!hydrazide

A solution of 4.18 g (4.99 mmol) of 5-4-(carboxymethoxy)benzyl!-3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 24a) and equimolar amounts oftriethylamine and chloroformic acid isobutyl ester, prepared in 250 mlof tetrahydrofuran at 0° C. under exclusion of moisture, is graduallycombined with further cooling with a solution of 74 mg (2.49 mmol) ofhydrazine in 50 ml of tetrahydrofuran. After one hour of stirring at 5°C., another hour at room temperature, and 30 minutes at 45° C., themixture is cooled, concentrated, and taken up in ethyl acetate. Afterfiltering, the mixture is repeatedly washed with water and 0.1Nhydrochloric acid. Finally, the product is chromatographed on silica gelwith ether/hexane, thus obtaining 3.17 g (76% of theory) of a colorlessoil.

Analysis

Calcd: C 61.77; H 8.55; N 6.7; O 22.96.

Found: C 62.26; H 8.52; N 6.61.

(b) N,N'-Bis 4- 3-(carboxymethyl)aza-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxyacetyl!hydrazide

The free complexing agent is obtained in accordance with the procedureoutlined in Example 1e in a 78% yield as a white powder, melting point205° C. (decomposition).

Analysis

Calcd: C 49.72; H 5.62; N 10.08; O 34.56.

Found: C 49.77; H 5.67; N 10.03.

The gadolinium complex, as well as its salts, are obtainedquantitatively as described in Example 1e.

Gd Complex

Analysis

Calcd: C 38.92; H 3.97; N 7.89; O 27.05; Gd 22.15.

Found: C 38.71; H 3.91; N 7.87; Gd 22.34.

Sodium Salt of the Gd Complex

Analysis

Calcd: C 37.75; H 3.71; N 7.65; O 26.23; Na 3.14; Gd 21.49.

Found: C 37.82; H 3.70; N 7.72; Na 3.09; Gd 21.13.

N-Methylglucamine Salt of the Gd Complex

Analysis

Calcd: C 40.39; H 5.68; N 7.63; O 31.99; Gd 14.29.

Found: C 40.56; H 5.70; N 7.54; Gd 14.13.

EXAMPLE 40 (a) 1,12-Bis- 4- 3-(tert-butoxycarbonylmethyl)aza-5-bis(tert-butoxycarbonylmethyl)amino-2-bis(tert-butoxycarbonylmethyl)aminomethyl!pentamethylenephenoxy!-4,9-diaza-5,8-dioxododecamethylene

At 0° C., 770 mg (4.96 mmol) of succinic acid dichloride is gently addeddropwise to 8.36 g (9.99 mmol) of 5-4-(3-aminopropoxy)benzyl!-3,6,9-tris(tert-butoxycarbonylmethyl)-3,6,9-triazaundecanedioicacid bis(tert-butyl)diester (Example 18b) in 100 ml of toluene and anequimolar amount of triethylamine. Then the mixture is heated briefly toreflux, filtered, the organic phase thoroughly washed with water, andchromatographed on silica gel. Finally, 7.62 g (82% of theory) of acolorless oil is obtained.

Analysis

Calcd: C 62.92; H 9.05; N 7.48; O 20.52.

Found: C 61.63; H 8.95; N 7.56.

(b) 1,12-Bis 4-3-(carboxymethylaza)-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxy!-4,9-diaza-5,8-dioxododecamethylene

As described for Example 1e, the free complexing agent is obtained in a78% yield.

Melting point: 220° C. (decomposition).

Analysis

Calcd: C 53.20; H 6.77; N 10.69; O 29.32.

Found: C 52.82; H 6.80; N 10.76.

The gadolinium complex, as well as its salts, are obtainedquantitatively as described in Example 1e.

Gd Complex

Analysis

Calcd: C 43.05; H 5.1; N 8.65; O 23.72; Gd 19.43.

Found: C 43.28; H 5.1; N 8.74; Gd 19.51.

Sodium Salt of the Gd Complex

Analysis

Calcd: C 41.92; H 4.85; N 8.42; O 23.10; Na 2.76; Gd 18.92.

Found: C 42.63; H 4.81; N 8.28; Na 2.71; Gd 18.57.

N-Methylglucamine Salt of the Gd Complex

Analysis

Calcd: C 43.06; H 6.30; N 8.17; O 29.34; Gd 13.11.

Found: C 43.91; H 6.19; N 8.29; Gd 13.06.

EXAMPLE 41 (a) 3,6-Diaza-3,6-bis(tert-butoxycarbonylmethyl)-4- 4-(3- 5-2-oxo-2,3,3a,4,6,6a-hexahydro-1H-thieno3,4-d!imidazol-4-yl!valerylamino!propoxy)benzyl!suberic AcidBis(tert-butyl)diester

341.4 mg (1 mmol) of N-hydroxysuccinimidobiotin (Pierce Chem. Comp.) iscombined with 679.9 mg (1 mmol) of3,6-diaza-3,6-bis(tert-butoxycarbonylmethyl)-4-4-(3-aminopropoxy)benzyl!suberic acid bis(tert-butyl)diester (Example1c) in 6 ml of DMF and stirred overnight. Then the reaction solution isconcentrated by evaporation and chromatographed on silica gel(toluene/glacial acetic acid/ethyl acetate/methanol=6:4:4:3). Thefractions, purified by thinlayer chromatography, are combined, thesolution is evaporated under vacuum, and dried over KOH. Yield: 695 mg(78% of theory).

Analysis

Calcd: C 60.97; H 8.34; N 7.73; O 19.42; S 3.54.

Found: C 61.05; H 8.29; N 7.71; S 3.30.

(b) 3,6-Diaza-3,6-bis(carboxymethyl)-4- 4-(3- 5-2-oxo-2,3,3a,4,6,6a-hexahydro-1H-thieno3,4-d!imidazol-4-yl!valerylamino!propoxy)benzyl!suberic Acid

453 mg (0.5 mmol) of compound 41a is combined with 3 ml oftrifluoroacetic acid and stirred for 30 minutes. The mixture is thenprecipitated with dry diethyl ether, the precipitate is washed withdiethyl ether, and dried. Yield: 298 mg (90% of theory).

Analysis

Calcd: C 52.85; H 6.40; N 10.27; O 25.81; S 4.70.

Found: C 52.79; H 6.49; N 10.20; S 4.59.

The gadolinium complex is prepared according to the procedure describedin Example 1e.

Analysis

Calcd: C 43.10; H 4.82; N 8.38; O 21.05; S 3.84; Gd 18.81.

Found: C 43.01; H 4.79; N 8.45; S 3.97; Gd 18.47.

EXAMPLE 42 (a)3,6,9-Triaza-4-(4-hydroxybenzyl)-3,6,9-tris(carboxymethyl)undecanedioicAcid

7.80 g (10 mmol) of3,6,9-triaza-4-(4-hydroxybenzyl)-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid bis(tert-butyl)diester (Example 9f) is dissolved in 100 ml oftrifluoroacetic acid and, after one hour, precipitated with diethylether. After chromatoggraphy on silica gel in ethanol/concentratedammonia/water (8:1:1), the purified fractions are passed over"Amberlite" IR 120 (H⁺), and the acidic eluate is freeze-dried. Yield:4.09 g (82% of theory).

Analysis

Calcd: C 50.50; H 5.85; N 8.41; O 35.24.

Found: C 50.39; H 5.85; N 8.34.

(b) Gadolinium Complex of3,6,9-Triaza-4-(4-hydroxybenzyl)-3,6,9-tris(carboxymethyl)undecanedioicAcid

0.50 g (1 mmol) of the complex acid disclosed in Example 42a isdissolved in 40 ml of water and combined with 181 mg (0.5 mmol) of Gd₂O₃, stirred for 30 minutes at 80° C., filtered, and the filtrate isfreeze-dried.

Yield: 0.65 g (99.4% of theory).

Analysis

Calcd: C 38.58; H 4.01; N 6.43; O 26.92; Gd 24.06.

Found: C 38.39; H 4.02; N 6.47; Gd 24.11.

EXAMPLE 43 a) Bis-1,10-{4-2,6-di(bis-t-butoxycarbonylmethylamino)-4-(t-butoxycarbonylmethyl)-4-azahexamethylene!-phenoxy}decane

9.36 g (12 mmol) of4-(4-hydroxybenzyl)-3,6,9-triaza-3,6,9-tris(tert-butoxycarbonylmethyl)undecanedioicacid-bis-(tert-butyl)diester (Example 9f) is dissolved indimethylformamide (100 ml), mixed with 0.40 g (13.2 mmol) of sodiumhydride (80% in paraffin, and, after adding 1.80 g (6 mmol) of1,10-bis-bromodecane, it is stirred overnight at 80° C. The solvent isconcentrated by evaporation in a vacuum, and the residue ischromatographed on silica gel (ether/hexane/triethylamine 12:8:1). 5.6 g(55% of theory) of a colorless oil is obtained.

Elementary analysis:

Cld: C 65.07; H 9.26; N 4.95.

Fnd: C 64.82; H 9.48; N 5.06.

b) Digadolinium complex of bis-1,10-{4-2,6-di(bis-carboxymethylamino)-4-(carboxymethyl)-4-azahexamethylene!phenoxy}-decane,tetrasodium salt

5.09 g (3 mmol) of the deca-tert-butyl ester described in Example 43a isdissolved in methanol and mixed with 5.4 ml of 10N sodium hydroxidesolution (54 mmol) and refluxed for 2 hours. After cooling the solution,methanol is concentrated by evaporation in a vacuum, water is added, andit is adjusted to pH 3 with Amberlite IR 120® (H⁺ form), mixed with 1.09g (3 mmol) of Gd₂ O₃ and complexed for 2 hours at 80°. The solution,cooled to room temperature, is adjusted to pH 7 by adding diluted sodiumhydroxide solution. The solution is freeze-dried. 4.89 g of colorlesslyophilizate is obtained.

Yield: 98.4% of theory

Water content (Karl Fischer): 7.5%

Gd content (AAS): 19.3%

Elementary analysis (relative to anhydrous substance):

Cld: C 40.37; H 4.34; Gd 20.51; N 5.48; Na 6.00.

Fnd: C 40.49; H 4.61; Gd 20.17; N 5.62; Na 5.84.

EXAMPLE FOR NMR DIAGNOSTICS IN VIVO Imaging of Gallbladder and a ColonCarcinoma by NMR Tomograph

A hairless mouse (Balb/c nu/nu, female, 20 g) with subcutaneouslyimplanted HT29 colon carcinoma received intravenously 0.1 mmol/kg of thegadolinium complex of3,6,9-triaza-4-(4-hydroxybenzyl)-3,6,9-tris(carboxymethyl)undecanedioicacid (Example dissolved in 200 μl of physiological phosphate buffer.

Images were produced prior to and after administration of the contrastmedium with a spin echo sequence (T_(R) =400 msec, T^(E) =30 msec) inthe region of the liver and the tumor. The studies were performed with a2 tesla NMR tomograph of the company General Electric.

The scan shows three photographs: one prior to and two afteradministration of the contrast medium. The gallbladder, 30 minutes afteradministration, is clearly distinguishable from the surrounding livertissue. The tumor exhibits immediately after administration signalamplification in the marginal zone whereas a marked signal enhancementcan be perceived after 30 minutes in the entire tumor.

What is claimed is:
 1. A compound of general formula I ##STR10## wherein n and m in each case are the numbers 0, 1, 2, 3, and 4;X stands for a hydrogen atom and/or a metal ion equivalent of an element of atomic numbers 21-29, 42, 44 of 57-83; R¹ and R², being different, are in each case a hydrogen atom or a straight-chain, branched, or cyclic, saturated or unsaturated C₁ -C₂₀ -alkylene group, said alkylene group optionally containing imino, phenylenoxy, phenylenimino, amido, hydrazido, ester group(s), oxygen, sulfur and/or nitrogen atom(s) and is optionally substituted by hydroxy, mercapto, imino, epoxy, oxo, thioxo and/or amino group(s), said alkylene group exhibiting at the end either a moiety of general formula I_(A) or I_(B) ##STR11## wherein at least one of R¹ and R² is said alkylene group having at the end thereof a moiety of formula I_(A) or formula I_(B) ; with the proviso that n and m jointly result in 1-4 and that at least two of the substituents X mean a nonradioactive metal ion equivalent; or a salt thereof with at least one inorganic and/or organic base or amino acid.
 2. A method for enhancing a magnetic resonance image comprising administering to a patient a pharmaceutical composition comprising:(a) an effective amount of a compound of the formula I ##STR12## wherein n and m in each case are, independently, 0, 1, 2, 3 or 4;X in each case is a hydrogen atom and/or a metal ion equivalent of an element of atomic numbers 21-29, 42, 44 or 58-70; R¹ and R² are different and mean, in each case, a hydrogen atom or a straight-chain, branched, or cyclic, saturated or unsaturated C₁₋₂₀ -alkylene group which optionally contains imino, phenylenoxy, phenylenimino, amido, hydrazido, ester group(s), oxygen, sulfur and/or nitrogen atom(s) and is optionally substituted by hydroxy, mercapto, imino, epoxy, oxo, thioxo and/or amino group(s), said alkylene group having at the end a second group of formula I_(A) or I_(B) ##STR13## with the provisos that n+m, in each case, is 1-4, and at least two of the substituents X are said metal ion equivalent; or a salt thereof with an inorganic and/or organic base or amino acid; and (b) a pharmaceutically acceptable carrier.
 3. A method of enhancing an X-ray image comprising administering to a patient a pharmaceutical composition comprising:(a) an effective amount of a compound of the formula I ##STR14## wherein n and m in each case are, independently, 0, 1, 2, 3 or 4;X in each case is a hydrogen atom and/or a metal ion equivalent of an element of atomic numbers 21-29, 42, 44 or 57-83; R¹ and R² are different and mean, in each case, a hydrogen atom or a straight-chain, branched, or cyclic, saturated or unsaturated C₁₋₂₀ -alkylene group which optionally contains imino, phenylenoxy, phenylenimino, amido, hydrazido, ester group(s), oxygen, sulfur and/or nitrogen atom(s) and is optionally substituted by hydroxy, mercapto, imino, epoxy, oxo, thioxo and/or amino group(s), said alkylene group having at the end a second group of formula I_(A) or I_(B) ##STR15## with the provisos that n+m, in each case, is 1-4, and at least two of the substituents X are said metal ion equivalent; or a salt thereof with an inorganic and/or organic base or amino acid; and (b) a pharmaceutically acceptable carrier.
 4. A compound according to claim 1, wherein n in each case is 0, m in each case is 1 and R² is H.
 5. A compound according to claim 4, wherein R¹ exhibits at its end a moiety of formula I_(a).
 6. A compound according to claim 4, wherein R¹ exhibits at its end a moiety of formula I_(b).
 7. A compound according to claim 1, wherein n in each case is 0, m in each case is 1 and R¹ is H.
 8. A compound according to claim 7, wherein R² exhibits at its end a moiety of formula I_(a).
 9. A compound according to claim 7, wherein R² exhibits at its end a moiety of formula I_(b).
 10. A compound according to claim 1, wherein said alkylene group contains one or more phenoxy groups.
 11. A compound according to claim 1, wherein said alkylene groups contains one or more phenylenimino groups.
 12. A compound according to claim 1, wherein said alkylene group is a straight-chain or branched, saturated or unsaturated C₁₋₂₀ -alkylene group optionally containing imino group(s), amido group(s), hydrazido group(s), ester group(s), oxygen atom(s), sulfur atom(s) and/or nitrogen atom(s) and is optionally substituted by hydroxy, mercapto, imino, epoxy, oxo, thioxo and/or amino group(s).
 13. A compound according to claim 1, wherein said alkylene group contains a cyclic saturated structure.
 14. A compound according to claim 1, wherein said alkylene group contains a cyclic unsaturated structure.
 15. A method according to claim 2, wherein said compound is a gadolinium complex of bis-1,4- 4- 2,6-di bis(carboxymethyl)amino!-4-(carboxymethyl)azahexamethylene!phenoxy!butane.
 16. A method according to claim 2, wherein said compound is a gadolinium complex of N,N'-bis 4- 3-(carboxymethyl)aza-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxyacetyl!hydrazide.
 17. A method according to claim 2, wherein said compound is a gadolinium complex of 1,12-bis 4- 3-(carboxymethylaza)-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxy!-4,9-diaza-5,8-dioxododecamethylene.
 18. A compound according to claim 1, wherein said compound is a digadolinium complex of bis-1,10-{4- 2,6-di(bis-carboxymethylamino)-4-(carboxymethyl)-4-azahexamethylene!-phenoxy}decane.
 19. A method according to claim 3, wherein said compound is a gadolinium complex of bis-1,4- 4- 2,6-di bis(carboxymethyl)amino!-4-(carboxymethyl)azahexamethylene!phenoxy!butane.
 20. A method according to claim 3, wherein said compound is a gadolinium complex of N,N'-bis 4- 3-(carboxymethyl)aza-5-bis(carboxymethyl)amino-2bis(carboxymethyl)aminomethyl!pentamethylenephenoxyacetyl!hydrazide.
 21. A method according to claim 3, wherein said compound is a gadolinium complex of 1,12-bis 4- 3-(carboxymethylaza)-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxy!-4,9-diaza-5,8-dioxododecamethylene.
 22. A method according to claim 2, wherein said compound is a digadolinium complex of bis-1,10-{4- 2,6-di(bis-carboxymethylamino)-4-(carboxymethyl)-4-azahexamethylene!-phenoxy}-decane.
 23. A method according to claim 3, wherein said compound is a digadolinium complex of bis-1,10-{4- 2,6-di(bis-carboxymethylamino)-4-(carboxymethyl)-4-azahexamethylene!-phenoxy}-decane.
 24. A pharmaceutical composition comprising a compound according to claim 1 and a pharmaceutical carrier.
 25. A composition according to claim 24, wherein said compound is a gadolinium complex of bis-1,4- 4- 2,6-di bis(carboxymethyl)amino!-4-(carboxymethyl)azahexamethylene!phenoxy!butane.
 26. A composition according to claim 24, wherein said compound is a gadolinium complex of N,N'-bis 4- 3-(carboxymethyl)aza-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxyacetyl!hydrazide.
 27. A composition according to claim 24, wherein said compound is a gadolinium complex of 1,12-bis 4- 3-(carboxymethylaza)-5-bis(carboxymethyl)amino-2-bis(carboxymethyl)aminomethyl!pentamethylenephenoxy!-4,9-diaza-5,8-dioxododecamethylene.
 28. A composition according to claim 24, wherein said compound is a digadolinium complex of bis-1,10-{4- 2,6-di(bis-carboxymethylamino)-4-(carboxymethyl)-4-azahexamethylene!-phenoxy}-decane. 